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I have an Emachines desktop. It turns on for about 3 seconds then off. All the fans turn on and the hard drives spin up. Theres no POST or any display signal. I removed all the RAM sticks but nothing changed. I replace the PSU but also same problem. I am guessing its the motherboard? Could it be anything else?

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Not an expert on this, but I had similar problems with a self-built system I had once, and it was the motherboard. – GreenMatt Apr 23 '11 at 20:52
^Thanks. Answers like these is what I need. I dont want to but a whole new replacement motherboard, to find out that its not the problem. – Chris Tarazi Apr 23 '11 at 20:55
possible duplicate of Computer Turns on Briefly then right back off again. – Wuffers May 7 '11 at 17:09
I've had happen over the years many times, and it's always been the RAM, power supply, or motherboard. If you eliminated the other two, I would put about 95% certainty on the motherboard. – BlueRaja - Danny Pflughoeft May 7 '11 at 18:23

Remove all hardware connected to the motherboard except for the processor, one memory module, power supply.

Remove all add in cards (note the positions), disconnect (power and data cables) all hard drives, optical drives floppy etc.

If there is on board video, remove the video card and connect the monitor to the on board video port, otherwise leave the video card in place

See if you get a bios post. If not try another memory module.

If you get a bios post start adding hardware back in one at a time and test for bios post each time until you find the bad hardware that prevents a post screen.

If no post, you will need spare parts (Video card, PSU, CPU, Mobo) to troubleshoot it.

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I have tried that and still nothing. – Chris Tarazi Apr 24 '11 at 19:01

Another possible reason is the CPU is overheating. Now I know it is a long shot but it is possible. The reason for the CPU could be the motherboard as you mention or the CPU cooling system isn't working correctly.

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How could I find this out? – Chris Tarazi Apr 24 '11 at 0:16
Overheats in 3 seconds? – Moab Apr 24 '11 at 3:11
^It doesn't feel hot so I don't think that's it. – Chris Tarazi Apr 24 '11 at 3:33
@ct64116: What doesn't? The heatsink? If the heat-paste is cheap or was applied incorrectly, then the heatsink won't be getting hot... – BlueRaja - Danny Pflughoeft May 7 '11 at 18:22
up vote 1 down vote accepted

Turned out to be the motherboard. Replaced with a new one and the computer is up and running.

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