Testing power supply voltage

[stymie222]

I have had this build running for about 3 years. It will no longer power up. I am aware of procedures and will unplug everything to the minimum and start from scratch.

I am having problems finding the proper way to check the main 24 pin/ATX power connector from the power supply. I have the pin outs, but for instance, when checking the voltage, can I use any ground and then any 3,5 or 12 volt positive pin ?

I searched this forum but cannot find a stickey or post on this procedure. Thanks

[glc]

If it won't start connected to the motherboard, you need to disconnect the 24 pin main and the 4/8 pin CPU aux connector. Leave the drives connected to act as a load. Use a paper clip from the green wire to any black wire to jump it, then plug it into the wall/turn the rocker switch on. If it doesn't start, it's dead. If it does start, then probe the voltages, any black is fine for ground.

[stymie222]

Thanks

As instructed the unit powered up. I unplugged all power to hard drive, cd/dvd-roms, PCI express vid card and it does not power up. Motherboard green LED is on.

Motherboard bad ?

[glc]

Can you be a bit more specific, please? I'm a bit confused.

[stymie222]

As instructed- I unplugged the main 24 pin connector and aux power connector from the motherboard.
I jumped the green wire and ground on the 24 pin connector. The PC powered up. Power supply fan, case fan came on among others.

Power supply shows voltage at all 12V DC and other outputs. One 5Volt pin was 4.98, others 3.3 V with jumper installed.

Just to mention- I jumped power pins- no power.

Sounds like Motherboard




Thanks

[glc]

Okay - manually jumpering the PSU, it started - but using this procedure:

PROBLEMS with a NEW BUILD? Try This!!

it did not start? Yes, that's most likely the motherboard, but pull the video card and ram and try again. If I'm not mistaken, you can even pull the CPU and the PSU should at least start.

[stymie222]

Now I know how to check my Power Supply.

This is an older intel D955XBK MB. That means new MB, Ram, and might as well CPU.

Never ending, but have to have it.

[glc]

Won't start connected to the mobo no matter what you do?

Examine the board for bulging or leaking caps, and look for burn marks.

[stymie222]

Could not find any visible problems with old board. I tried a new Motherboard and exact same problem. Will not power up. Not one bit of power to even move the fan slightly. Moved power plug to several other outlets.

I double and triple checked polarity of power switch,led,hd wires to header on MB. Shorted power switch pins, no power.

This has got to be a power supply problem. Voltages at 24 pin power plug read OK, but I guess under a load it dies.

Any suggestions ?

[glc]

Try a different power supply.

What brand and model is this PSU?

[stymie222]

Its an OxCLIO 460 Watt recommended from here about 3 years ago.

Thanks, I'm about to pull my hair out. Whats left of it.

[glc]

It's very possible it has gone bad, even though it starts when not connected to a motherboard.

[stymie222]

New Antec supply on the way. Will post results ASAP.

I will tear the old OxCLIO down and post findings too.

Thanks for your time.

[stymie222]

PC powered up with new Power Supply. New Gigabyte mother board and did not have to repair windows.

I will check the old power supply for faults. Sometimes, checking small DC voltage can be tricky. I may have misread and they could also be intermittant.

Thanks very much for your help.

[David M]

I once had my PSU not power up while plugged into the motherboard because the BIOS did not allow the PSU to power up. I think it was that I had not connected something that the mobo requires. Anyways...

Pull the CMOS battery and use the BIOS reset jumper (if you have one) and reset the BIOS back to its factory settings. Try this before you assume that the motherboard is bad.

Another idea is to test a working PSU on your suspect motherboard or to take your suspect PSU and test it with another working motherboard.

I would try all these tests before you junk the motherboard or the PSU.