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I was recently given this computer by a friend to fix. It was working fine until the other day when it abruptly stopped working overnight.

When it receives power, everything in the system receives power, but no video is displayed and no POST codes are beeped. All fans are properly spinning and I can hear the hard drives kick on as well.

My first thought is that it might be the power supply. I hooked it up to a PSU tester, but it reported everything was fine.

I next attempted to get some sort of POST code out of it. I disconnected all drives and then removed one of the pairs of RAM (dual channel - two pairs making four sticks total) then the other, then finally removing all RAM from the system. No combination of RAM removal generated any POST.

Next, I thought it might be some sort of issue with the CMOS battery, so I popped it out and replaced it with a known good battery to no avail.

Finally, I thought it might be the video card so I completely removed the PCIe video card and tried it with the on-board video, but again, absolutely nothing changed.

I'm assuming the only thing I haven't ruled out is the motherboard. I've visually inspected it and I see no blown or leaking capacitors or anything obvious. Short of ordering a replacement motherboard, is there any way to verify that it's the culprit?

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There are no simple ways to verify a motherboard other than process of elimination, and it sounds like you have done that already. –  MaQleod Aug 29 '11 at 20:02
    
I'm a bit hesitant about ordering a new motherboard for it. I've Googled and found people in very similar situations that did pretty much the same diagnostic steps as me and were led to the conclusion that it was the motherboard only to replace it to no avail. I'd like to avoid ordering an $80 part and having to say "oops, we're no closer to fixing the problem than we were before". –  DWilliams Aug 29 '11 at 21:24

1 Answer 1

To get a POST beep code you'll need at least:

  1. a working power supply;
  2. a functional CPU;
  3. a functional motherboard.

So far you have tested the PSU, and are solely focusing on the motherboard as the culprit. You have made no mention of any testing of the CPU.

To confirm that just the motherboard is faulty, I would use another power supply and another CPU that were known to be working in another system, and test with the suspect motherboard.

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