Testing power supplies

[Odyssey]

Here is an post found on another board which (I think) tells how to test a PS. If anyone has any comment or guidance before I give it a try, it would be very much appreciated.

"Just to let you know, I also had a constant green light on the MOBO. I completely removed the PSU from the unit, and jumped the green wire to a black one, and plugged in the PSU. Nothing happened. I tried it an an old PSU just to check if the jumping worked and it did. The fan on that PSU with the green and a black wire jumped, powered on. So, it would appear that there is a problem with the Dell PSU. I spoke to a Dell parts supplier (I'm in Ireland, he's in the UK) and he said that the Dell PSUs are a big weakness, which I'd already heard from other users. I told him I had upgraded the video card to a 256MB Nvidia GEForce 5200 and he said that that could have caused problems for the PSU, which operates at 250w. Anyway, I've ordered a new PSU which I should have this week and hopefully it will work. He suggested downgrading the videocard to a 126MB one. I asked him about installing a more powerful PSU that would output around 400w, but he said their technician had tried this on another Dimension with bad results, so he suggested sticking to a 250w one. I'll let you know what happens with the new PSU.

 

[DaveFarquhar]

I've successfully used that method to test power supplies, but I will offer this caveat: Dell power supplies use a different pinout than standard ATX, even though the plug is the same. Don't put an off-the-shelf power supply into a Dell, or you'll blow the power supply or the motherboard, possibly both.

But the testing method your message describes works great for standard ATX power supplies. Whenever I'm faced with a computer that won't power up, it's one of the first things I try.

Dave Farquhar

http://dfarq.homeip.net

 

[paparazi]

Odyssey
This is a very basic test and does not in any way fully test the PSU on all rails and under load.
In your case is seems to have correctly confirmed a dead PSU but this test could "pass" but and the PSU could still remain dead in the PC.

I do have a couple of comments regarding your conversation with Dell.
An FX5200 is a basic entry level graphics card, even a 256mb version is a relatively low power consumer compared to other GPU's, suggesting you downgrade to a 128mb version was at best, ill informed and poor advice.

Also suggesting that a 400watt replacement had "bad results" when a higher wattage quality replacement is exactly what you need, is also poor advice (running a PSU at 95% is always going to worse than running a higher power unit at 55%)
Martin

Martin

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