How to test PSU voltage without digital tester

[RegEdit]

Is there a boot CD that will test PSU voltage? I don't like using a digital tester because you risk snapping the motherboard.

 

[NYJimbo]

Generally speaking, most of the time when you need to test a PSU its because the system isnt booting, how can you test PSU voltage (assuming something like that would be possible) with a boot CD if the machine isnt booting ?

What do you mean "snapping the motherboard" ?

 

[RegEdit]

Generally speaking, most of the time when you need to test a PSU its because the system isnt booting, how can you test PSU voltage (assuming something like that would be possible) with a boot CD if the machine isnt booting ?

What do you mean "snapping the motherboard" ?

I've never snapped a motherboard by unplugging the 24 pin power connector and reconnecting it, but these things worry me sometimes.

As part of my basic diagnostic I test the PSU, but maybe that's overkill if there's no reason to suspect a bad PSU. What do the big box stores do? I guess I just assumed that they test the PSU because their diagnostic description says "test all hardware". Maybe they mean "if it works then consider it tested".

 

[Martyn]

Keep a good known psu for testing purposes. Trying to measure voltages doesnt test it under load situations.

 

[NYJimbo]

I've never snapped a motherboard by unplugging the 24 pin power connector and reconnecting it, but these things worry me sometimes.

As part of my basic diagnostic I test the PSU, but maybe that's overkill if there's no reason to suspect a bad PSU. What do the big box stores do? I guess I just assumed that they test the PSU because their diagnostic description says "test all hardware". Maybe they mean "if it works then consider it tested".

Well, I can understand the concern about damaging stuff, I tear down laptops all day and you know how tiny and delicate that stuff is. But you have to get past your fear and just be careful, PSU testing or swapping on a bad boot or non-boot condition on a desktop is pretty much mandatory for proper diags. Now having said that, I never test a PSU unless I think the PSU could be part of the problem. I doubt VERY much that GeekSquad or others really fully "test" anything, they just run some stupid GS disk that might excercise the hardware and try to talk to things and see if they respond. I can't see GS pulling PSU cables and hooking them up to a tester every time they get a box in.

 

[coffee]

I find alot of times that hooking up the tester takes as much time as taking a known good p/s and hooking it up instead. So, I just always have one available for testing and just hook up a p/s and power on the system.

Best Regards,

coffee

 

[RedFoxComp]

Keep a good known psu for testing purposes. Trying to measure voltages doesnt test it under load situations.

Yeah, was just going to mention that. Those PSU testers are cool looking, but there is no load so the only thing it will test is if it's completely dead.

 

[shamrin]

Is there a boot CD that will test PSU voltage? I don't like using a digital tester because you risk snapping the motherboard.

Save yourself some time and take PSU "testing" out of your routine. The meters, like the one you show in your picture, don't put a load on the system so a positive test with one doesn't mean that the PSU is good. Conversely, I can't think of any case where that tester has shown me a negative result on a computer that was bootable.

 

[sassenach]

Use a multimeter and pin out diagrams. No need to unplug anything to carry out the testing.

 

[johnrobert]

If your computer is totally dead no cpu fan etc
Believe me you psu is toast no need for fancy equipment

 

[NYJimbo]

Use a multimeter and pin out diagrams. No need to unplug anything to carry out the testing.

A multimeter can only check two points at a time and many times you cannot get to a point without disconnecting something.

 

[RedFoxComp]

I made a script to launch prime95 and furmark portable for 20 seconds. This pulls more power from the PSU than the user ever will.

If it makes it through 20 seconds of that kind of draw then the PSU is ok in my books. It's also a good test to see if the PSU is powerful enough for the installed hardware.

 

[Rob_NNCC]

back to the OPs question, Speedfan and other monitors should tell you voltages. PLUS, any decent non OEM motherboard should tell you the voltages in the BIOS.

BUT, looking at the voltages for bad things usually requires an oscilloscope and it is way beyond what is necessary. The script mentioned that runs futuremark and prime95 is not only a great idea, but would be welcome on my flash drive.

 

[NYJimbo]

back to the OPs question, Speedfan and other monitors should tell you voltages. PLUS, any decent non OEM motherboard should tell you the voltages in the BIOS.

Speedfan and the others only work if you can fully boot the O/S. The term "decent" means nothing when Joe SixPack brings you a computer and the BIOS doesn't show you voltages. I got a Dell tower here yesterday that shows me nothing. I know what to do next, but no software can help me now.

Likewise those tools can only report voltages if there is a known place to probe and that the program actually interrogates the hardware. There is a huge number of boards out there which will not report voltages because either the software doesn't have the code written to probe it or there is no known point to probe.

 

[RegEdit]

OK. I thought maybe there was a boot CD out there that tests voltage offline. It looks like no.

I don't come across many PC's that shows BIOS voltages.

 

[npinc]

You can't test a power supply properly without a proper power supply tester. For one you can't test for power good, which is a very important measurement to have. For another you can't test for tolerances. Very slight variations can produce drastic results.

Load is irrelevant when you have improper regulation and you can't "load" it properly via software. What about the rails? How do you test rails properly through software? You can't. There's so much to know about power supplies (case in point, Kyle at HardOCP made a complete fool out of himself when he bought himself a new toy and tried to pose as a power supply expert).

 

[PaulRome]

PC Wizard 2012 has power supply monitoring. A version of PC Wizard is included in mini xp (hirens) just not sure which version.