Computer powers on then off

TempestAU

Reputable
Jul 5, 2014
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4,510
Recently went to turn my computer on, turns on then off after about 2secs.

It turns on, the CPU lights up, fan starts spinning , then it powers off.
The PSU still idles the fan and has its light on.

I have replaced the PSU, problem still remains.

I then just replaced the motherboard just because i was desperate to fix it, problem still remains.

Ive tried powering it on with no graphics card, 1 Ram, no ram, no Hdd , all naked other then cpu. I have also tried by-assing the power switch, in all the above scenarios, and i still have this problem.

I have also read the guide for common problems in this case on this site.
Pretty desperate for help right now.
Is it my CPU? or am I missing something obvious?

Thanks in advance.
 
PSU? - can't be that because you've changed it.
Mobo? - ditto.

So, logically, it has to be a component you have not replaced.
That means CPU or RAM (hard drive excluded because that would not cause system to shut down immediately after start up.

Even bad RAM (or even no RAM at all) wouldn't cause near-instant shutdown, so that leaves the CPU as the hot favourite.