I have a friends computer I am upgrading. When I went to plug in the power supply, the power supply started up. There is no switch on the supply and the puter will not post. Is this a mobo issue or a P/S issue? I don't have a spare supply to test. I have unplugged all the cards and drives so there is nothing but the power supply hooked up, and it still does it. Is there any other testing I can do? Thx

Any lights?

Any BEEPS?

Remove the RAM and see if it BEEPS.

Do you have the 24/20 pin as well as the 8/4 pin PSU plugs in the motherboard?

Is the PSU powerful enough for your upgraded components?

The only lights are the ones on the front of the puter. The CPU fan is running. No beeps. Removed the RAM, no difference. I unplugged all the cards and drives and no diff. This is an older computer and it has only the 20 pin power connector. Still no post.

Assuming that the motherboard or case speaker works and you get no Beeps without RAM then...

Could be the PSU but more likely the motherboard. Assuming there is a working speaker in there.

Try clearing the CMOS on the motherboard.

Are you sure that the CPU is compatible with the motherboard?

Ya, this computer has run in the past. It died on the owner and he thought it was the PSU, so this is a different PSU. That is really the only thing that changed prior to me adding a new H/D & DVD drive. This is the second time I have come across this dilemma. Will CMOS still work if it doesn't post? How do I reset, Just pull out the battery and put it back in?

Some boards have jumpers or switches but pulling the battery should do it as well.

This is weird. I pulled out the battery and when I plugged the PSU in it didn't automatically start(good sign). So I hit the power button and the PSU fired up but nothing else. CPU fan and GPU fan didn't start. I held in the power button for 3 seconds and it turned off. No beeps no post.

I have come to the conclusion (after trying a new PSU and a different GPU that the motherboard is fried.Thx for your suggestions.

Thanks for the update.

Let us know how it goes or if we can help further.

Converting 20 pin to 24 pin , power connector.

I have seen alot of different sites sellin these adaptors, but also ran across a few sites that suggest using the 20 pin on the 24 pin socket, just leave the first 4 empty? or using a 20 + 4 pin unit? any suggestions here?

I have seen this illustration: dont know if it works however, does anyone know?

http://www.hardwareanalysis.com/content/image/11254