PSU problems? or something I don't know.

I will refer to my computers as #1 and #2.

I have got a couple of Pentium 4 computers at home as my secondary computer. I recently found a better motherboard so I decided to swap the CPU's around (moving the CPU from computer #2 to computer #1).

Funny thing is, when I turn on my computer (#1), it stays on for a couple of seconds, goes through the normal POST sequence, then just shuts down and loses power.

Even funnier is that I thought it was the power supply, so I took the CPU and put it back in the other computer (#2). Now both computers are doing the same thing.

I notice something else. If I turn the computers on right after they shut off, they stay on for about 4 seconds or so, whereas if I turn on the computer after a couple minutes of waiting, they stay on for a longer time.

I suspect a PSU problem, but since this is happening to both computers, I'm not sure anymore. Is it possible that it's a CPU problem or something else? They both POST fine. They just turn off for no reason. I've tried resetting the BIOS and everything. I've even tried using a new power outlet. If it really is the power supply, I would have a hard time understanding how both of my power supplies died.

Keep in mind that computer #2 was running this morning, and computer #1 has not been used for a couple of months now.

update: I'm running my computer with no RAM at all, and it's still doing it. This is very weird.

 

OMG i can't believe this. It's a thermal shutdown.

That is ridiculous. I actually burned my knuckle on the CPU after listening to some guy's suggestion. Ouch, but it's working now...

If it doesn't shut down in 10 minutes it should be good.

 

i was gonna ask if you put the fan with thermal paste on it...

 

I actually did, but the mounting bracket makes it so that the heatsink actually does not touch the CPU.

I have switched to a new heatsink which is shaped better for that particular mounting bracket, and it works. Thank goodness for thermal shutdowns, or else I'd be feeling pretty stupid right now. (I'm actually already feeling a bit silly.)

Thanks anyways.