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Windows 7: PSU Testing

05 Dec 2011   #1
Microsoft MVP

Windows 7 Ultimate X64 SP1
PSU Testing

information   Information
Here is a rewrite of the PSU Test. PSU - How to Test

warning   Warning
Before attempting the following PSU test, power system off and pull the power plug or flip the PSU switch off, whichever applies.

warning   Warning
Do not open the PSU's case! It can carry a lethal dose of power for days. This means it could kill you.

I have been struggling with a new build and got to PSU testing.

Here's how to test yours if suspect. Press the latch on the side of the main connector and wiggle it out of its socket. The PSU won't power on unless the main connector is attached to the motherboard or you jumper the main connector as shown below. The common thing to use is a paper clip bent in a "U" shape and can be inserted in either side of the plastic connector.


There will be one green wire, jumper it to any black one. This will allow the PSU to power up and its fan will run. If it has an on/off switch confirm it is ON. If the EPS 12V 4/8 pin is connected to the motherboard your CPU fan may run.

It is a better test if you use a digital multimeter after you have the PSU running to check actual volts output at the pins. Touch the "-" lead to any black wire pin then the "+" to each of the other colored pins and take a reading. They should be 5% of listed voltages.

The diagrams below show the current ATX configurations in use.

PSU Testing-psu-main-pinout.png

My System SpecsSystem Spec
05 Dec 2011   #2

Windows 8.1 Pro RTM x64

You should always ensure that you use a digital multimeter to measure the voltages. An analogue one can be used, however due to its low resistance when compared to a digital model, a true reading will not be obtained. For the best results, testing should be carried out under normal load conditions. Testers are available which can apply an artificial load, and which simply plug into the relevant cables. An example of such a tester is shown below:

PSU Testing-capture.png

These should be available from Amazon, NewEgg, or any good computer hardware stockist.

My System SpecsSystem Spec
05 Dec 2011   #3

Windows 7 Ultimate x64, & Mac OS X 10.9.2

i have a far more effective way! it goes "Daaaaaaaaaaad" (im not 12 by the way lol) But him being an electrician and having every gizmo under the sun he can test it properly, modern testers even have so pc tester sockets lol

great post though!
My System SpecsSystem Spec

05 Dec 2011   #4
Microsoft MVP

Windows 7 Ultimate X64 SP1

Since this is a kind of self-help forum my post is aimed at the "casual" builder, the pros have all the gizmos. This is a good way to test without having to buy a $14-$40 tool which may be used once and put in a drawer to be sucked in by a black hole.
It will also provide needed experience so one can "do it himself", which is my method.
My System SpecsSystem Spec
05 Dec 2011   #5

Windows 10 Pro

Good post Britton, and yeah it's good if you don't have a testor. I would warn that if you're uncomfortable with messing with electricity, leave the testing to the pros.

Bookmarked :)
My System SpecsSystem Spec
05 Dec 2011   #6

Windows 10 Pro x64

Good post Britton !
My System SpecsSystem Spec
05 Dec 2011   #7
Microsoft MVP

Windows 7 Ultimate X64 SP1

thank you, thankyou!
My System SpecsSystem Spec
13 Jan 2012   #8
Microsoft MVP

Windows 7 Ultimate X64 SP1

Shortly after I posted this my brother told me his PC wouldn't turn on any more. It was a failed PSU found by the test method posted. I have now bought a PSU tester. - Computer Case, Power Supply, Computer Accessories, Networking, Peripherals. Price, Quality, and Services.
My System SpecsSystem Spec

 PSU Testing

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