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Build Your Own PC: Hard Disk Drives, CD/DVD Drives, and Floppy Drives

Last updated on 12 February 2008

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This article consists of six pages. You can access the other five pages by clicking the relevant hyperlink below.

Step 4

The Disk Drives

The Hard Disk Drive

A modern computer cannot function without at least one hard disk drive (HDD) containing copies of the operating system and the applications it runs. Long gone are the days when home computers stored everything they needed on floppy disks or tapes.

I personally prefer Maxtor (now owned by Seagate), Western Digital, and Seagate hard disk drives.

Like RAM, the hard disk drive is a system critical device that has to function perfectly. Any manufacturer consistently making drives that failed would go out of business very quickly. That is probably why it is so difficult to buy a bad hard drive.

Note well that hard drives with a high revs-per-minute rating (7200RPM+) get much hotter than drives with a lower rating (5400RPM). Therefore, be sure to install a drive with a high rev rating in its bay so that it has space around it. Do not cram it in between other drives. If you have odd problems with the system, consider buying and installing a cooling unit for such a drive. If you don't require fast hard-drive access speeds, buy a drive with a 5400RPM rating. They are less expensive, and may well last longer. Note that most laptop/notebook computers currently (March 2007) come with 5400RPM drives, but 7200RPM drives are becoming more common.

The method of configuration and installation depends on the type of hard drive being installed. The methods differ for the three main types - IDE ATA, serial ATA (SATA), and SCSI. IDE ATA hard drives, also known as parallel ATA (PATA) hard drives are still being manufactured, but are in the process of being replaced by SATA hard drives in home PCs.

All you have to do is make up your mind which make, type (IDE, SATA, or SCSI), and size of drive is supported by your computer and suits your needs best. You can purchase it from a retail outlet, mail-order company, or from an auction website.

Note well that you should erase the content of any hard drive you purchase second-hand properly with a specialised low-level utility such as Eraser, which is free, because, even though the drive is formatted, any illegal content that the previous owner had on the drive, such as illegal pornography, will be recoverable by disk-editing software. It would be a good idea to do likewise with a new hard drive, because it may have been returned to the manufacturer with data on it, repaired, and resold as new. It is not too improbable a set of circumstances that your computer could be stolen and the police recover it and examine the hard drive forensically to find out if the original owner's name can be found, and you then get arrested for having illegal images on it.

A hard drive is a crucial and delicate piece of hardware that can sometimes arrive non-functional, so I would pay the extra and buy it from a retail outlet so that it can easily be returned instead of sending it by mail or by using a courier service. I personally always purchase brand new hard drives, because, with a second-hand drive, I won't know how its previous owner treated it.

If you want to use the system for graphic-intensive work, video editing, or CAD work, you should buy an SCSI hard drive. If the motherboard does not have an inbuilt SCSI Controller, you will have to buy a PCI adapter card such as are provided by Adaptec.

The installation of SCSI drives is more complicated than an IDE drive, because SCSI devices are daisy-chained together and therefore each SCSI device has to be given an ID number, and the devices on each end of a daisy chain of devices has to be 'terminated' so that the computer knows where the chain begins and ends, so, if you don't know how to do that, make sure that you buy a boxed product that comes with an installation manual. You should also be able to search the web for and find tutorials on SCSI configuration and installation. You can use the Google search box provided at the top of this page (with its Web radio button enabled). A search term such as install + scsi + hard + drive (as is) should bring up plenty of links

Most tutorials come in the PDF format, so you should have the free Adobe Acrobat PDF Reader or another PDF reader installed in your PC.

A hard disk drive is easy to install whether it is boxed (the product comes with cables, screws, driver software, 3.5 inch caddy for 5.5 inch bays), or bare, OEM (the product comes with no accessories at all).

If you purchased a boxed retail motherboard, it should have come with all of the cables necessary to install all of the hard drives and CD/DVD drives that it supports. Windows will load the IDE device drivers automatically, so all you require is a bare drive with the four screws needed to attach it to one of the 3.5 inch bays in the case. Two IDE ribbon cables with connection points for four drives, and a floppy disk drive cable are usually provided with the motherboard. However, new computers that come with round cables for hard and floppy disk drives are becoming the norm.

Both IDE ATA and serial ATA (SATA) drives are attached directly to the motherboard by special ribbon cables, or to a PCI adapter card.

The type of IDE ATA ribbon cable shown in the image below on the left can accommodate two drives each. There is a second connector that connects to a drive in the middle of the cable.

Round cables for IDE drives that can accommodate two drives or just a single drive are available, but I have not seen much use made of them. An image of these round cables is shown a little further down this page.

The ribbon cable shown in the image on the right is for a floppy disk drive. It has a twist in the conductors that is clearly visible at the end of the connector that must always be fitted to the floppy disk drive itself.

You can also purchase an add-on PCI card for an IDE drive if you want to install more than the usual maximum of four drives - or if you want to use a higher mode of the IDE ATA standard that is not supported by the motherboard. Serial ATA (SATA) drives use thinner ribbon cables that can only accommodate a single drive. Look further down this article to see an image comparing the two types of ribbon cable.

There is more information on SATA hard disk drives further down this page.

Note that you can purchase bay conversion units that allow you to fit 3.5 inch hard drives in 5.5 inch bays that usually only house CD/DVD drives.

A serial ATA (SATA) hard drive has its own much thinner cable that can only be used with one drive.

Note that information on the differences between the two different types of ribbon IDE cables, and information about serial ATA hard drives is provided further down this page. This is important information, and has to be made use of when installing a hard disk drive.

Heat and cooling

You can connect a mixture of four IDE hard drives or CD/DVD drives to most most ATX motherboards (some allow more), and you can install a PCI IDE card that allows you to install more. Most current motherboards also provide four SATA connectors for SATA hard drives or CD/DVD drives. (SATA CD/DVD drives are becoming more common.) But before you add more drives make sure that the power supply unit (PSU) won't be overstretched, and make sure that they are installed with overheating in mind.

If you install more than one hard drive, you should take great care with how they are installed and kept cool. Most recent 7200RPM high-speed IDE ATA drives generate a significant amount of heat, which is a major cause of drive failure.

You should leave at least a 10mm gap between drives, which can mean drilling mounting holes in new positions on the drive bays. You can also add extra cooling fans that are installed so that they blow air over the drives.

Or, if your computer's motherboard has the correct ports, you can add one or more external USB or FireWire hard drives.

If the motherboard doesn't have the required Hi-Speed USB 2.0 or FireWire ports, you can install a PCI adapter card that provides them.

How to configure and install a hard disk drive (HDD)

Installing disk drives in the drive bay of a computer's case and attaching them to the motherboard and the power supply unit with the correct cables isn't difficult, but it should be done properly and with care. Don't ever use force! All of the connectors are keyed nowadays so that they can only fit into a particular socket the right way around. If you have to force anything into place, you're probably not installing it properly.

Note that it is now possible to purchase round IDE disk drive cables (HDD and CD/DVD cables) instead of traditional ribbon cables. They can be used with an ATA drive of any specification. They take up less space tha ribbon cables and therefore don't inhibit the flow of air inside the case as much.

The image below shows the individual cables. As you can see, as with ribbon cables, they can accommodate two drives each. Single-drive cables are also available. For some reason, they come in a wide variety of garish colours, such as red and blue.

Problems with the new round IDE cables

From the alt.comp.hardware.pc-homebuilt newsgroup

"Hi, I recently bought a set of CoolerMaster round IDE cables and I'm wondering if anyone has the same experience of the 45cm ones that I have. Trying to fit them on two drives close together is almost impossible without great force which didn't seem right to me. I spaced the drives apart and then only after cutting back some of the rubber shield would they bend enough to fit on the drives, if I had the drives right next to each other they just won't bend enough. The 60cm [cable] I bought for the DVD and CD burner doesn't have this problem. Also I managed to pull two of the tabs off when I needed to swap drives around. I certainly won't be buying anymore CoolerMaster cables in a hurry. I was going to buy the cheaper ones but decided on these as I thought they would be better. Wish I'd have saved a few quid now."

How to mount a hard disk drive

Note well - use screws of the correct length to secure a hard drive in a bay. If the screws are too long they can easily penetrate the drive and render it useless. Bare OEM hard drives usually don't come with screws or cables, so purchase the correct screws from the dealer if you didn't get a packet of screws with your case or motherboard.

Below are the kind of instructions that are provided in the manual that is provided with a retail boxed hard drive, or that can be downloaded from the manufacturer's website for OEM drives that are supported by the vendor instead of the manufacturer. These instructions were provided in the manual of a Seagate drive.

"You can mount the drive in any orientation [vertically, horizontally, any way up] using four screws in the sidemounting holes or four screws in the bottom-mounting holes... Follow these important mounting precautions when mounting the drive: Allow a minimum clearance of 0.030 inches (0.76 mm) around the entire perimeter of the drive for cooling. Use only 6-32 UNC mounting screws. The screws should be inserted no more than 0.200 inch (5.08 mm) into the bottom mounting holes and no more than 0.14 inch (3.55 mm) into the side mounting holes. Do not over-tighten the mounting screws (maximum torque: 6 inch-lb). Do not use a drive interface cable that is more than 18 inches long."

Although you can mount hard disk drives in any position you like, I prefer to mount them horizontally with the label on the top and the printed circuit board (PCB) on the bottom.

Note that if a drive has been run for a long time in one position and the orientation is changed, there's a slightly increased chance of mechanical trouble because the bearings may have become acclimatised to the original orientation and have worn in a particular way. The new orientation could load the bearings slightly differently and they may cause trouble or suffer from accelerated wear.

How to configure and install a hard disk drive (HDD) - continued...

The method of configuration and installation depends on the type of hard drive being installed. The methods differ for the three main types - IDE ATA, SATA, and SCSI.

IDE ATA hard drives are still manufactured, but are in the process of being replaced by SATA hard drives in home PCs.

Most motherboards have two IDE ports, each of which supports two IDE drives, one or more of which can be a CD or DVD drive. You can add additional drives by installing a PCI adapter card, such as those made by Promise. The additional drives are attached to the IDE ports on the adapter card, which uses its own BIOS to configure the drives.

Click here! to view annotated images of motherboards on this site showing the two IDE ATA channels, and one floppy disk drive channel. Click your browser's Back button to return to this point on this page.

There is usually a diagram on the hard drive itself (of the kind illustrated below), showing the jumper settings to configure it as a master or slave device. The configuration table is fixed to the top or bottom of the drive.

The Master, Slave, and CS Enabled (Cable Select) jumper settings are clearly shown on the Maxtor drive shown above.

Note that due to political correctness that is offended by the words Master and Slave, new drives will probably be using the terms Primary and Secondary instead, but I will continue using the clearer Master and Slave. A PC with four drives would have a primary master, a primary slave, a secondary master, and a secondary slave, but if Primary and Secondary replace the traditional terminology, the four drives will be called a primary primary, a primary secondary, a secondary primary, and a secondary secondary, which is somewhat absurd.

The Cap Limit setting shown in the image above automatically sets the drive to a system's maximum size capacity, because many systems cannot run huge drives. This particular DiamondMax Plus drive (5400RPM, 2MB cache, 12.6ms disk access time), has a capacity of 300GB that unmodified Windows 9x systems, which run the FAT16 or FAT32 file systems, won't be able to run as a single (unpartitioned) volume. Windows XP, running its NTFS file system, can run such a drive unpartitioned if the motherboard's BIOS setup program allows it. Windows XP was released in October 2001. Nevertheless, you need to install Service Pack 1 (SP1) or Service Pack 2 (SP2), which incorporates it, to be able to use drives larger than 137GB.

All of the versions of Windows Vista provides large drive support for drives larger than 137GB.

For more information on what you need to know in order to upgrade a hard disk drive on a particular PC, visit this Upgrade Checklist on this site.

If the BIOS setup program doesn't provide large drive support, reflashing it with the latest BIOS file from the PC manufacturer or motherboard manufacturer's site might fix the problem. Otherwise, installing a new PCI IDE adapter card of the kind made by Promise, or a new motherboard that has a BIOS capable to recognising such a large hard drive is the only remedy.

I prefer using the sound Master/Slave settings to configure drives, but the easiest way to configure and install an IDE ATA 66/100/133 hard drive, which has to be installed using an 80-conductor ribbon cable (not an old-style 40-conductor cable), is to set the drive's jumpers to the Cable Select setting.

When jumpered for Cable Select, the cable plus the jumpering determines which is the master drive and which is the slave drive. The master drive will go to the black connector on the 80-conductor ribbon cable, and if a slave is used, it will be connected to the ribbon's middle (grey) connector. The ribbon's blue connector fits to the motherboard.

Note that as long as two hard drives are themselves jumpered to enable the Cable Select setting, you can swap them from the master to slave positions on the ribbon cable.

If the Cable Select setting is not being used, the boot hard drive containing the operating system (Windows), always installed on the Primary IDE Channel on the motherboard, must be set as the master drive.

The boot hard drive is the drive (or the partition on a hard drive) on which the operating system is installed. The boot hard drive must always be installed on the Primary IDE Channel.

Placing a jumper across two pins on a hard drive activates a particular setting. Sometimes removing a jumper will activate a setting. The two white jumpers, on the port face of the hard disk drive shown below, can be seen clearly next to the power supply port with its four pins on the far right side of the drive.

All current hard drives have a keyed socket that one of the keyed plugs coming from the power supply unit fits.

The diagrams below show where a 40-conductor or an 80-conductor ribbon cable and the plug from the power supply unit are connected on a standard hard drive.

In the first case, for older drives, the 40-conductor ribbon cable has a red line down one edge that has to be connected to the side of the connection socket where Pin 1 is located, which is usually the side closest to the power connector's socket. In the second case, for current drives, the cable is "keyed" so that it can only fit in the socket one in one way.

In the colour image of a hard drive above, you can see the cutting for the "key" in the IDE connector on the far right. The power plug from the power supply unit fits into the connector on the far left.

IDE cables are now usually (but not always) keyed so that they fit only one way into the motherboard or to the drive itself. If this is the case, there is a large ridge in the middle of each connector and a smaller ridge at each end that matches a cutting on the IDE connection points on the motherboard and the drive itself.

With the drive fixed in a drive bay in the case, other than plugging it to the power supply, all you have to is attach one end of the connector of an IDE cable to the motherboard's Primary IDE Channel (the boot drive must go on the primary channel as shown in the motherboard's manual), and (if a 40-conductor cable is being used) attach one of the two other connectors along its length to the drive itself.

In other words, with this particular cable, as long as the side with the red line along its length is attached to Pin 1 on the motherboard's Primary or Secondary IDE Channel, you can attach a master or a slave drive to either the end or the middle connector.

If an 80-conductor cable is being used, the hard drive must be attached to an end connector according to the colour code, which is usually the blue connector connected to the motherboard and the black connector connected to the hard drive. The middle connector is used for slave drives.

Note that a modern IDE ATA drive can be installed in the case in any orientation - it doesn't matter which way up it is as long as there is the required space for cooling purposes between it and the case. However, most technicians install a drive with its printed circuit board facing down.

The drive's user manual, supplied with the drive or downloaded from its manufacturer's website, will provide mounting and installation instructions.

Also note that most quality ATX PC cases allow you to remove the drive bay and screw a drive in it with two short screws on both sides. But, in a tower case, if the drive bay is fixed in it, there will probably be a gap in the plate to which the motherboard is fixed that will allow you to screw in the screws from that side. This is usually a clumsy business, so you should install the drive in the bay when you have removed the plate to install the motherboard. If you have an OEM drive that came without screws, remember to make sure that you only use short ones. Screws that are too long could penetrate the drive and destroy it. If you purchased a PC case it will have come with a container full of different types of screws and the stand-offs on which the motherboard is mounted.

When installing a boot drive that contains the operating system (Windows, Linux, etc.), you get a 40-conductor ribbon cable the correct way round by attaching the side of the ribbon cable that has the red line running down its length to Pin 1 of the Primary IDE Channel, which is illustrated in the motherboard's manual. The side of the cable with the red line along its length is then attached to the drive itself on the side of the drive that is closest to the power supply connection. - See the images above, one of which is a drawing, that illustrate this.

80-conductor ribbon cables are installed according to a colour code. A connector (usually blue) is always attached to the motherboard and the opposite end connector (usually black) is connected to the master hard drive, with the middle connector used for a slave drive.

Below is a diagram from an MSI motherboard manual showing the location of the two IDE channels on the motherboard. The figure 1 shows where Pin 1 is located on each channel. This motherboard was designed to support ATA 33 hard drives, and so comes with the 40-conductor ATA 33 ribbon cables.

You can download the manuals for the latest MSI motherboards free of charge from http://www.msi.com.tw/.

To read an article on recommended IDE device configurations that discusses which drives should be installed on which IDE channels for the best performance, visit -

http://www.pcguide.com/ref/hdd/if/ide/confRecommendations-c.html

Reminder - If you are using 40-conductor ATA 33 IDE cables, as long as the correct side with the red line down its length is connected to Pin 1 on the motherboard, and the red line on the cable is the side closest to the power supply plug on the drive, it does not matter which end is connected to the drive, or which end is connected to the motherboard or PCI adapter card. But if you are using 80-conductor IDE cables (for ATA 66 / 100 / 133 hard drives), and you have not enabled the Cable Select option, you must also connect the end with the blue plug to the motherboard, and the master drive must be attached to the other end - which is black - and a slave drive must be attached to the middle connector - which is grey. - You cannot attach a master drive to the middle connector. You can use an 80-conductor cable with an ATA 33 hard drive, but you cannot use a 40-conductor ATA 33 cable with drives running in ATA 66 and higher modes of operation.

As I mentioned earlier, there are two types of IDE ribbon cable.

The earlier type of ribbon cable is used on ATA hard drives running ATA (UDMA) 33 and earlier ATA modes. This cable has 40 conductors in the ribbon. But hard drives using the ATA (UDMA) 66/100/133 modes of operation require the new cables that have 80 conductors in the ribbon, 40 of which are used to shield the others from electromagnetic interference.

Note that all new computers will come with the 80-conductor ribbon or round cables, or with an SATA cable if an SATA drive is installed.

Cable Select support

As long as both of the IDE channels are enabled in the BIOS, and all of the other IDE settings in the BIOS are set to Auto, which they should be, you should not need to configure anything else. The drive will begin operating as soon as the system, which has at the very least RAM module(s) and a video/graphics card installed, is powered up.

If you have two drives installed on a cable, one has to be configured as the master (M), and the other has to be configured as the slave (S). If you have two hard drives on the same cable, they will both work in the same ATA data transfer mode as the slowest drive.

If you are using the 80-conductor ATA 66 cable that allows the Cable Select (CS) option on the drive to determine its status by its position on the cable, you obviously cannot place any drive on any connector as with the master-slave option, because it is the drive's position on the cable that configures it.

It is possible to have a CD or DVD drive set as master on the Secondary IDE Channel, with a hard drive on the same cable set as the slave. If you only have one CD or DVD drive, it is best not to have it on the same cable as the boot hard drive on the obligatory Primary IDE Channel.

To read an article on recommended IDE device configurations that discusses which drives should be installed on which IDE channels for the best performance, visit -

http://www.pcguide.com/ref/hdd/if/ide/confRecommendations-c.html

All 80-conductor IDE cables meet the ATA specifications and hence support the Cable Select feature automatically.

Visit this discussion of cable select for more information -

http://www.pcguide.com/ref/hdd/if/ide/conf_CS.htm

Installing an SATA hard drive

Installing an SATA hard drive is the simplest of all of the installations that requires no configuration of the drive itself. Unless a PCI adapter card is used, it just involves connecting the drive to the motherboard with a single SATA cable (that cannot accommodate another drive), and connecting a power cable from the power supply unit to the drive's power connector. More information on SATA drives is provided a little further down on this page.

Note that if your PC has an elderly motherboard that only supports the original SATA standard, a SATA II drive, which has a theoretical data transfer speed of 300MB/s, will work at the slower SATA 150MB/s data transfer speed. However, to do so, some SATA II drives require a jumper on the back of the drive to be set. The jumper, which will be stored on inactive pins at the back of the drive, will have to be placed across two pins that will be indicated by a diagram on the drive. Setting the jumper makes it possible for the drive to operate at the slower speed. You can consult your PC's or its motherboard's user manual to find out if it supports SATA or SATA II. If your PC only supports SATA and you have an SATA II drive, look for a diagram on the drive that shows you how to set its SATA jumper.

Further information on installing hard drives

For more information on IDE cables visit these two sections of the PC Guide site. -

Standard (40-Conductor) IDE/ATA Cables -

http://www.pcguide.com/ref/hdd/if/ide/conf_Cable.htm

Ultra DMA (80-Conductor) IDE/ATA Cables -

http://www.pcguide.com/ref/hdd/if/ide/confCable80-c.html

And here are pages on other sites with tutorials on how to install hard drives. -

http://www.informationweek.com/LP/showArticle.jhtml?articleID=181502411

http://www.tweak3d.net/articles/howtoinstallhd/

http://www.harddriveupgrade.com/

http://www.thepc.info/harddrive_upgrade.html

Hard drives: Partition and format

Click here! to go directly to information on how to partition and format a hard disk drive on Page 6 of this article. Use your browser's Back button to return to this point on this page.

Serial ATA (SATA) hard disk drives

The connection limitations of IDE ATA (parallel ATA/PATA), with its system of master and slave drives, is not longer applied to serial ATA (SATA) drives.

Serial ATA uses a single cable per drive.

You cannot attach more than one drive to a cable. While it is no longer necessary to configure the drive using jumpers, there may be a jumper setting that can reduce the capacity of the drive for motherboards that only support a certain size of drive.

The image below shows cables used to connect an SATA hard disk drive to the motherboard.

The installation is simplicity itself - just attach the keyed serial cable to the drive and the motherboard, and attach a power connector from the computer's power-supply unit to the drive. The cable is keyed so that one end can only connect to the motherboard and the other end to the drive, so it can't be install the wrong way round. The image below shows the connection points on a motherboard for four SATA hard drives.

Hard disk drive problems - SATA hard drives

There are several Q&As that discuss installation and other problems to do with SATA hard drives on the Hard Disk Drive Problems pages on this site. Look on Page 2 and Page 3.

New-style Serial ATA power supply units

New ATX12V 2.0 power supply units that have SATA power cables coming directly from them are available.

The new power supply units have new Serial ATA power-line connectors for both hard-disk and optical (CD/DVD) drives.

For the time being, hard drives capable of using the new power cable will also have the standard four-pin power socket. However, a conversion cable will always be available so that an old-style power supply can be used with a new Serial ATA hard drive.

Note that if your PC has an elderly motherboard that only supports the original SATA standard, a SATA II drive, which has a theoretical data transfer speed of 300MB/s, will work at the slower SATA 150MB/s data transfer speed. However, to do so, some SATA II drives require a jumper on the back of the drive to be set. The jumper, which will be stored on inactive pins at the back of the drive, will have to be placed across two pins that will be indicated by a diagram on the drive. Setting the jumper makes it possible for the drive to operate at the slower speed. You can consult your PC's or its motherboard's user manual to find out if it supports SATA or SATA II. If your PC only supports SATA and you have an SATA II drive, look for a diagram on the drive that shows you how to set its SATA jumper.

Click here! to go directly to information about the new SATA hard disk drives on the Disk Drives pages of this site.

Direct Memory Access (DMA)

In a Windows 95/98/Me system, the DMA option is enabled or disabled by clicking the device's name in the Windows Device Manager (under the headings +Disk drives and +CDROM). Click the + sign to reveal the drives. Under the Settings tab you will find a checkbox called DMA. Use your mouse to put a tick in it and reboot to enable the setting. All of the latest drives will support DMA, so make sure that it is enabled, because, as it allows the drives to bypass the processor and have direct access to the RAM, it improves the system performance significantly.

From a system performance point of view, it important to make sure that you enable DMA properly, which is not as straightforward as you might think. You can simply enable DMA for a particular drive in the Device Manager, but there is a DMA setting in the registry too. There are several articles on this subject in Microsoft Knowledge Base on this subject.

The following article on Microsoft's site explains DMA in Windows XP.

DMA Mode for ATA/ATAPI Devices in Windows XP -

http://www.microsoft.com/whdc/device/storage/IDE-DMA.mspx

How do I enable DMA mode on CD and DVD burner drives? -

"DMA (Direct memory access) mode is a high performance mode for transferring data to and from devices, in particular, to CD and DVD burner devices. The burner devices can function in either DMA or PIO modes. DMA mode allows the processor to transfer large pieces of data with very little software overhead - therefore requiring low CPU utilization. In this mode, high speed burning can be performed in background with other programs running. PIO mode requires CPU processing for every few bytes sent to the device, so that CPU utilization becomes very high when trying to burn at high speeds." -

http://www.onthegosoft.com/dma_setting_nt.htm

Windows [Vista] Help and How-to - Turn Direct Memory Access (DMA) on or off -

"Direct memory access (DMA) is usually turned on by default for devices such as hard disks and CD or DVD drives that support DMA. However, you might need to turn on DMA manually if the device was improperly installed or if a system error occurred." -

http://windowshelp.microsoft.com/Windows/en-NZ/Help/...mspx

If you have an old hard drive that does not support DMA (Direct Memory Access), you should not enable it for a drive on the same cable - a hard drive or CD drive - that does support it - unless the motherboard's chipset and IDE drivers support independent timing, because you are likely to experience problems that might be very difficult to rectify.

For example, if you have an elderly motherboard that only supports the earlier PIO modes of operation instead of the UDMA modes required for the use of DMA, do not enable the DMA option for any hard disk drive - even if the drive itself is a UDMA drive that supports DMA. - If the motherboard does not support the DMA modes of operation, you cannot use them for any drive - even if the drive itself supports DMA.

The modes of operation will be given in the motherboard's user manual.

But if you have a UDMA2 (ATA 33) hard disk drive, or higher, which supports DMA, and which is also running on a motherboard that supports DMA, and if the motherboard's chipset supports independent timing, which all relatively new motherboards do, you will be able to install a drive that does not support DMA (only supports the PIO modes of operation) on the same cable, and have DMA enabled for the drive that supports it. But you should not enable DMA for the PIO-mode drive that does not support DMA.

You probably won't be able to find out if your motherboard chipset supports independent timing for drives working in different modes on the same cable. However, if you enable DMA for a hard drive that supports it while a hard drive that only supports the earlier PIO modes of operation is sharing the same cable, in a Windows 95/98/Me system, check the System Properties by clicking the System icon in the Control Panel.

If you see a message such as this under the Performance tab: - "Drive 1 is using MS DOS compatibility mode file system" - then the DMA option should not have been enabled.

Using MS DOS compatibility mode slows the system down. You can usually rectify the situation by clicking on the drive's name in the Device Manager (click the + next to the Disk drives heading), and then removing the tick in the DMA check box. You will have to reboot for the change to take affect. If the system is using its proper Windows mode of operation, the message, "Your system is configured for optimal performance" will show on the Performance tab of System Properties instead of the warning that Windows is using MS DOS compatibility mode.

The use of DMA became available with UDMA2 (ATA 33) hard disk drives, which support busmaster IDE drivers. If you have an earlier hard disk drive that supports only the PIO modes of operation up to PIO 4, you should not enable the DMA option for that drive, because it will not be able to use a busmaster IDE driver, and as such will cause problems that will probably involve having to boot in Safe mode to disable the DMA setting, or remove the IDE busmaster drivers in order to reinstall the proper ones.

IDE hard disk drives have reached UDMA5 (ATA 133). UDMA2 = ATA 33 - UDMA3 = ATA 66 - UDMA4 = ATA 100 - UDMA5 = ATA 133.

Any UDMA2 (ATA 33) or higher IDE hard disk drive will support DMA - as long as it is also running on a motherboard that supports the UDMA2 (ATA 33) or higher modes of operation.

You can purchase PCI cards that allow extra IDE drives to be fitted over and above the four that can be fitted to most motherboards. Such expansion cards make use of their own BIOS to configure the extra drives. Promise is the leading manufacturer of such cards.

CD/DVD/Floppy Disk Drives

An IDE (ATAPI) CD or DVD drive is connected (often appropriately configured by a jumper on the drive itself as master or slave drive) to one of the free connectors of the two IDE cables connected to the Primary and Secondary IDE Channels on the motherboard. As with a hard drive, a power cable from the power supply unit with the appropriate connector has to be attached to the drive's power socket.

An SATA CD/DVD drive (the latest interface) is connected to an SATA connector on the PC's motherboard. IDE and SATA hard disk drives were dealt with above.

If you need to know where to connect an IDE or SATA CD/DVD drive, consult the motherboard's user manual. If you don't have a copy, identify the make/model of the motherboard with a utility such as CPU-Z and search its manufacturer's site for the model involved. You should be able to download a user manual for it in the PDF format.

A CD or DVD drive has to be placed in a bay in the front of the case so that its face shows through one of the outlets that are the same size as the drive. In a new PC case, you will probably have to remove a removable metal cover that is punched out and can't put back, and a plastic cover in the front of the case that can be replaced if the drive is removed.

In order to provide sound, CD/DVD drives are connected to the a PC's sound card by a special single-wire connector. If the sound card is built into the motherboard, this connector will be connected to the motherboard as illustrated in its user manual. If you don't have a user manual for the motherboard in your computer you should be able to download a copy from its manufacturer's site, which you can locate by entering the manufacturer's name in a search engine. A Google search box has been provided at the top of this page. Enable its Web radio button if you want to search the web.

Note that if you install or replace a CD/DVD burner, make sure your new one is very solidly mounted. That is, don't use just two screws, use as many as you reasonably can on both sides of the drive, and even get some tiny lock washers at a hardware store and use them to make the drive less prone to vibrations. Vibrations have a significant negative effect on a CD/DVD burner compared to the effect they have on most other PC devices. The levels of vibrations that a hard drive will ignore will eventually cause your CD/DVD burner's lens to go off axis. And since CD/DVD burners are more expensive to repair than replace you will probably have to replace your burner before its time if you ignore this aspect of the installation.

Visit the CD/DVD drives section of this site for more information on them.

If you need confirmation or to see a video of a CD/DVD drive being installed, visit: http://www.buildyourown.org.uk/.

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A floppy disk drive (FDD) is installed in much the same way as a hard drive, except that it uses one of the small 3.5-inch outlets available in the front of the case instead of an outlet for 5.25-inch bay.

If the PC case is new, you will have to remove one of the plastic covers in the front of the case, which is about a quarter of the size of one the covers placed over the CD/DVD bays. You may also have to remove a punch-out metal cover.

The FDD has a special ribbon cable that can be identified by the twist in a couple of its strands in the middle of the cable near one end. - See the image below.

The end that has this twist closest to it is attached to the drive, and the other end is attached to the FDD Channel on the motherboard using the same convention as with hard drives. - The side of the ribbon cable with the red line down its length is connected to Pin 1 on the motherboard. The cable is connected to the drive correctly with the red line being closest to the power supply inlet on thedrive. The power supply provides a special small plug that connects into the FDD.

Note that if a hard drive's LED light on the front of the case, or the LED light on the FDD remain lit when the PC is first switched on, this usually means that the cable is the wrong way round - that the side of the cable without the red line along its length is connected to Pin 1 on the motherboard, or that side is connected closest to the power cable on the drive. The side with the red line should be connected to Pin 1, and the same side should be connected to the drive so that that is the side closest to the power plug on the drive. Having the cables the wrong way round in that way will do no harm, but having the hard-drive and floppy-drive cables not properly attached to the drive or to the motherboard has been known to render the drive permanently useless. So make sure that the plugs are pushed all the way into their sockets on the motherboard and the drive. They can easily be left half connected.

It is not necessary to install and connect the parallel, serial, and game ports with an ATX motherboard (as is the case with an older AT motherboard), because these ports are built into the motherboard. If you are installing an ancient AT motherboard, its manual will illustrate where to connect these ports on the board.

Note that you should not leave unused CD/DVD/FDD drive bays in the front of the case, or the expansion card outlets at the back of the case uncovered, because the gaps weaken the extraction of hot air by the PSU and case fan.

It is advisable to buy a CD-R/RW or DVD-R/RW drive instead of just a CD-ROM drive, because you can use it to play ordinary CDs (audio and data), and you can also use it to record ('burn') CD-R/DVD-R or CD-RW/DVD-RW discs. For instance, CD-R and DV-R disks are very cheap these days, especially when bought in bulk. You could use them to make regular back-up copies of your whole system so that it can easily be restored in the event of a wipe out.

CD/DVD writers usually come with the software required to use them, or you can download alternatives from the Internet from sites such as:

http://www.majorgeeks.com/

http://www.completelyfreesoftware.com/

http://www.tucows.com/

http://www.zdnet.com

More information...

For more information on IDE (ATA/UDMA) and SCSI hard disk drives, and IDE CD/DVD drives, visit the Disk Drives and Technical Stuff pages on this site.

How to install an external and an internal memory card reader

Click here! to go to information on this site on how to install external and internal memory card readers.

USB Flash Drives

Click here! to go to information on this site on USB Flash Drives

Google searches

If my descriptions are not clear enough for you, you'll be able to find many sites offering illustrated information on how to install computer components by entering a phrase such as "install a xxxx" (where xxxx stands for the device, such as RAM, hard disk drive, etc.) in the Google search box at the top of this page (with its Web radio button enabled).

PC Buyer Beware! Copyright © Eric Legge 2004-2008. All rights reserved.