Power Supply Testing

[bill of oz]

how do you properly test if a power supply is working or not?

does anybody have a link to an article or video that describes how to properly test if a power supply is working or not?

 

[jamesd1981]

Here you go - http://pcsupport.about.com/od/toolsofthetrade/f/powersupplytest.htm

 

[Darren]

You can also perform the paper clip test.

Bend a paper clip into a U shape and with the PSU unplugged insert one end into the ATX connection where the green cable is and the other end into one of the black cable connectors (there are several, just pick one). With the PSU powered off plug it back in and hook it up to a fan and switch the PSU on. If the fan spins up it is at least outputting some power. If it is then go on to the suggestions listed above.

Paper clip test is good to just test if a PSU is totally dead.

 

[beers]

Also keep in mind that the multimeter or PSU tester only checks voltage. A lot of times you'll have a unit that can provide an OK voltage but can't deliver sufficient amperage (the other half of the wattage equation) and will either buckle to not boot the PC or cause issues under load.

Most commonly you'll see shops swap with a known-good PSU to more quickly verify if the previous unit was indeed faulty.

 

[StrangleHold]

how do you properly test if a power supply is working or not?

does anybody have a link to an article or video that describes how to properly test if a power supply is working or not?

Like said, you can do the paper clip text just to see if it works. But it tells you nothing about when its under a load.

 

[The VCR King]

I like my power supply (1000 watt Cougar CMX) because if there is a power surge it keeps my PC on and just reboots it.

 

[Darren]

I like my power supply (1000 watt Cougar CMX) because if there is a power surge it keeps my PC on and just reboots it.

What.

No.

If your power surges due to lightning or something it'll probably just fry your computer if it's plugged in at the time. PSU's don't have that kind of tech built in (at least not yours).

If the power flickers or something like that your computer will lose power for just enough time to shut it down and it will automatically reboot, I think most if not all computers do that. Mine's done it a few times during storms.

 

[voyagerfan99]

If the power flickers or something like that your computer will lose power for just enough time to shut it down and it will automatically reboot, I think most if not all computers do that. Mine's done it a few times during storms.

Everything you have said is correct except for this part. Power settings in BIOS determine whether your computer resumes or stays off after loss of power. The settings specifically are:

-Power On
-Last State
-Stay Off

 

[Darren]

Everything you have said is correct except for this part. Power settings in BIOS determine whether your computer resumes or stays off after loss of power. The settings specifically are:

-Power On
-Last State
-Stay Off

Interesting. I guess now that I think about it I have seen that before when in the BIOS. Is this on by default for most motherboards?

 

[voyagerfan99]

Interesting. I guess now that I think about it I have seen that before when in the BIOS. Is this on by default for most motherboards?

The default for most motherboards is Stay Off.

 

[G80FTW]

I like my power supply (1000 watt Cougar CMX) because if there is a power surge it keeps my PC on and just reboots it.

If there was an actual "surge", the last thing you would want is for your computer to be on in the first place (let alone plugged in). And to that, what would be good about it keeping the PC on anyway if its going to reboot? Your data would have still been lost either way....

So had that been true, it would be pointless.

 

[Darren]

The default for most motherboards is Stay Off.

Interesting. In the computers I've worked with they tend to just restart. Thanks for clearing that up.

 

[johnb35]

Yeah, its always best for it to stay off after a power failure. A few times here the power has gone off and came back on and with in a few seconds went off again for a few minutes. It's times like this if you know a bad storm is coming then unplug it anyway. One time the power went off here and when it came back on, my pc wouldn't turn back on. I was like uh oh, not a good sign. So happens the outage loosened the power cable going into the power supply connection. I was lucky.

 

[Darren]

I normally unplug my computer during storms anyway but this is good info. Thanks. :good:

 

[spirit]

I normally unplug my computer during storms anyway but this is good info. Thanks. :good:

I'm a badass and leave it plugged in. So far so good, but you might not want to risk it.

 

[beers]

I like my power supply (1000 watt Cougar CMX) because if there is a power surge it keeps my PC on and just reboots it.

That's not a feature, rofl. The system lost enough wattage to quit processing but not to turn off completely.

Some PSUs with higher capacitance can keep your PC on for a second or so depending on load. Otherwise just get a UPS.

 

[Jamebonds1]

It would be better if you do multmeter. I have expesive multmeter but it will give me accurate. 10 dollar multmeter is very inaccurate so avoid it! (most of them) My experinced step.

1 Step, unplug everything that connection to PSU.

2 Step, short between green and black wires.

3 Step, plug in any one of external fan as load power.

4 Step, plug in power cable and turn on PSU.

5 Step, check on yellow, red and orange wire color with your multmeter. 12V, 5V, 3.3V. It should be in +/- 5% volt range.

NOTICE: You have to do math.
EX: (voltage * (Precent of range/100)) + voltage;
(12V * (+/- 5%/100)) + 12V;
(12V * (+/- 0.05)) + 12V;
+/- 0.6V +12V;
0.6V + 12V = Max 12.6V and -0.6 + 12V = Min 11.4V;
Max 12.6V and Min 11.4V.

 

[Okedokey]

It would be better if you do multmeter. I have expesive multmeter but it will give me accurate. 10 dollar multmeter is very inaccurate so avoid it! (most of them) My experinced step.

1 Step, unplug everything that connection to PSU.

2 Step, short between green and black wires.

3 Step, plug in any one of fan as load power.

4 Step, plug in power cable and turn on PSU.

5 Step, check on yellow, red and orange wire color with your multmeter. 12V, 5V, 3.3V. It should be in +/- 5% volt range.

NOTICE: You have to do math.
EX: (voltage * (Precent of range/100)) + voltage;
(12V * (+/- 5%/100)) + 12V;
(12V * (+/- 0.05)) + 12V;
+/- 0.6V +12V;
0.6V + 12V = Max 12.6V and -0.6 + 12V = Min 11.4V;
Max 12.6V and Min 11.4V.

A fan will provide next to no load to test 12V rail. Therefore your test is completely meaningless.

 

[Jamebonds1]

A fan will provide next to no load to test 12V rail. Therefore your test is completely meaningless.

I think I remember that some your comment is not always true and were meant to create issue.

That prove you're wrong about the external fan with no current amp.
http://media.digikey.com/pdf/Data Sheets/Sunon PDFs/80x80x25mm.pdf

And this,

https://www.youtube.com/watch?v=5FWXgQSokF4

It is necessary step to getting reliable voltage read and prevent from damaging PSU. Fan was used as load.

So unless I was wrong, please don't waste my time with unsource comment. I'm not stupid as I was.

 

[G80FTW]

I think I remember that some your comment is not always true and were meant to create issue.

That prove you're wrong about the external fan with no current amp.
http://media.digikey.com/pdf/Data Sheets/Sunon PDFs/80x80x25mm.pdf

And this,

https://www.youtube.com/watch?v=5FWXgQSokF4

It is necessary step to getting reliable voltage read and prevent from damaging PSU. Fan was used as load.

So unless I was wrong, please don't waste my time with unsource comment. I'm not stupid as I was.

Well....sadly he does actually have a point. A case fan will not pull any significant power from the system. 0.2 amps is almost nothing. While it is a load technically speaking, I personally wouldnt consider it enough of a load to use for testing.

Pulling 0.2 amps from a line that is made to supply 25A + is hardly a load for any power supply. You would be better off using a few HDDs.