PSU problems – PC power supply unit – Essential information

Power supply problems – Essential information on the power supply unit (PSU) of a computer

Showing the PSU options for a PC made by a system builder

Showing the PSU options for a PC made by a system builder. The 400W PSU installed in the machine might not be a high-quality unit, so research the make/model of PSU before choosing it. You can buy quality brand-name PSUs, such as Corsair, from Amazon and computer stores

The power supply unit (PSU) of a computer is its most vital component

The power supply unit (PSU) of a computer is its most vital component. All too often, it is the most neglected component. As with RAM memory, if it doesn’t work flawlessly all the time, nothing works properly for long. Hanging, freezes, Blue Screens of Death, sudden shut downs are common and can be caused by all sorts of things – overheating, the operating system (Windows, Linux, etc.) hardware (faulty PSU, hard disk drive, motherboard, memory, etc.) and software (device drivers, virus scanners, etc.)

The vital job of the power supply unit (PSU), usually just called the power supply, is to deliver a stable voltage to the PC’s components via its motherboard. If it does not do that, the PC will crash (stop working) and the components can be fatally damaged. If it fails to work, none of the PC’s components can be powered up.

For more detailed information on power supply units, including their installation, read the following article on this website. Otherwise, continue reading this post.

The power supply units – PSUs – used in desktop PCs –

Power Supply Units – PSUs

How to tell if a power supply is a quality unit

Due to the number of capacitors, diodes, rectifiers and other heavy circuitry, quality power supplies are relatively heavy units. Therefore, if it is a light unit, one that feels as if there isn’t much in its container, it won’t be a quality unit.

Quality brand-name PSUs have circuit protections built into them, the more expensive they are the more circuit protection they tend to provide, so units of quality should shut down if they are required to draw more power than they are able to deliver, but in older, low-quality or power supplies that have been given a wattage rating that they can’t deliver, they tend just to go bang, giving off a loud report.  Sometimes they can take all or some of the other components with them. Rarely, they can cause a fire when they go bang, which is why it is essential that you should always make sure that any PC you buy, new or second-hand, has a PSU of good quality.

Note that YouTube provides plenty of videos on PC power supplies, some much better than others. Here is a link to a relevant article:

How to Make Sure You Get the Right Type of PSU to Match Your Needs –

The power supply is usually the last component suspected of being the cause of a major problem

As you might have noticed when reading through the specifications of a new PC, the make/model of the power supply is hardly ever mentioned. Likewise, if the PSU is the cause of a major problem, it is usually the last component to be suspected. Unfortunate, because, if you are doing the troubleshooting yourself, due to your having known working components that you can swap out, you’ll no doubt try them all before you try using an alternative or new PSU. Which is why you should always make sure that any brand-name desktop PC that you buy has a high-quality PSU. Simply because it will usually outlive the working life of the machine and therefore will usually not be a factor in any problems.

So, as soon as you get a new desktop PC, open its case  – I have never come across a tool that identifies the PSU – and make a note of the make and model and look up reviews or information of it on the web. Quite often, to keep costs down, cheap, low-quality PSUs are used in even some quite expensive PCs.

The amount of power a PSU can deliver is measured in Watts (W)

The amount of power a PSU can deliver is measured in Watts (W), therefore the make/model always contains its maximum power output in W – 500W, 600W, 700W, etc., in its model’s name. The PSU has to be able to power all of the computer’s components with some overhead available in case all of them are used at once, which is not something that will happen very often.

Here is a power-supply calculator into which you add the components that your PC has. When you click its Calculate button, it calculates the Recommended Minimum PSU Wattage of such a system.

Enermax Power Supply calculator –

I would then buy a PSU that is rated at least 100W higher than the figure it calculates.

Calculation of the power that a particular system requires

I just did a calculation of the estimated wattage used by an old workstation of mine that uses an AMD Athlon X2 3800+ dual-core processor, an MSI (MS 7093) motherboard, a Nvidia GeForce GT 710 graphics card (PCI-Express x8) with passive cooling, four hard drives, a DVD writer, keyboard and mouse. Note that a graphics card with passive cooling (a heatsink-and-fan unit is not used) does not require an additional power connector (or two) from the power supply and therefore uses relatively little power. Powerful graphics cards require fan cooling.

The power requirement of my workstation is an estimated 275W. It uses a quality 350W unit made by Corsair, which leaves 75W of overhead. That is fine if the PSU is a quality unit. However, a cheap 400W or even 500W unit would probably be inadequate.

In short, always make sure that your desktop PC has a brand-name quality PSU, such as one made by Corsair or any other brand-name manufacturer of quality units.

If, say, you buy a 1000W quality PSU and your system can only draw a maximum of 650W – if all of its components are in use at once – you have 350W of overhead that won’t ever be used. The system will not draw 1000W just because it is available, only the amount of power it needs, so you can never buy a power supply that is too powerful.

Some of the settings of the Enermax Power Supply calculator explained

Nvidia and AMD are the two major manufacturers of graphics cards. SLI/CF for the graphics card in the power calculator stands for Nvidia’s and AMD’s SLI and CrossFire technology, respectively, that makes running multiple pairs of graphics cards in tandem possible, so you only select it if your PC uses more than one graphics card that are set to use that technology. FB DIMM for the RAM memory is only selected if the computer is using fully-buffered memory.

Most computers use normal or unbuffered memory.You can use the free CPU-Z  and Speccy tools to identify the RAM memory. Look under the SPD tab in CPU-Z to find out what the part number is of every installed DIMM module. Looking up the part number on the web will tell you if it is unbuffered or buffered.

Fully Buffered DIMM –