Computer shuts down abruptly and doesnt turn on after that

naveenakku

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Sep 16, 2011
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18,510
Hi, First time posting in this forum, I built a PC 4 months back with the following specs
Intel 2400
Motherboard GA-P67A-UD4-B3
single 4GB memory
Graphics Card Gigabyte HD6850

A couple of days back while I was watching a movie, the computer powers down, when I tried to turn on, it doesn't post to BIOS, I opened the case and saw that the Fan on the HD6850 doesn't turn, so I replaced it with Gigabyte 5450, No post to the bios. What I have also noticed was ocassionaly it posts to the bios, but turns off byitself and tries to turn on and the frequency of turn on and turn off decreases and finaly doesn't even turn on.
When I was able to go into the bios I checked the cpu temps,they were around 33 C when it turns off.

These are the things that I have already tried.

1.Bench tested the hardware, same issue.
2. Removed all unnecessary hardware hooked up only the necessary. same issue
3.Removed the thermal compound and put a fresh coat, same issue
4. No beeps
5. Clear CMOS by removing battery, jumping the CMOS Clear, holding the power button for 30 seconds. same issue.
6.Checked the voltages on the PSU, all are as per specification
7. I have only one ram stick, but I am not sure if that causes the issue because one time I was even able to load the operating system and after a couple of minutes it turned off.

I don't have any spare PSU or motherboard or ram, not sure what else needs to be tested, would like to get some suggestions from experts in this forums, much appreciated