Unstable Machine

[Chrisworld]

I've been trying to get a PC working here with no luck. The PC is a friends PC and I'm trying to get it to boot here after cleaning it up. The PC used to run, but after a while the CPU would overheat and the system would lock up. After I've taken it apart, cleaned all the dust out, reassembled it and reattached only the primary necessary fans, it's having some sort of trouble staying on. The PSU is 450 Watts. I've swapped two Intel P4's to see if one of the CPU's was bad. This was not the case. I reset CMOS several times, still not the case. I've unplugged one chassis fan, unplugged the Radeon Hd 3870 and went stock GPU, etc.. still nothing, the machine starts up for a few seconds then right back off it goes. I've tried another PSU even, and it too powers on and then off.

Are we looking at PSU's with not enough watts? The highest I have sitting around is 450, or are we looking at a trashed Mobo?

I've even tried putting some of the RAM (about 1.5 to 2 GB) and GPU (the 3870) into a dell I have sitting around and that thing doesn't even boot without it's stock pieces in place. POS.

[FTT]

Run things like Memtest or HDD testing softwares through your optical drive.

It sounds like hardware failure.

[kiosk]

Check the mainboard for bulging/leaking capacitors. They short-circuit internally, which sends the PSU in total panic mode, forcing it to shut down the whole system.

[rond36]

Need more system specs!

After you removed the CPU heat sink and fan did you properly apply fresh thermal paste when you re-installed it?

Is the CPU HSF plugged into the CPU fan header?

[66miranda]

Do those matter much?

[123456]

Yes... too little or too much thermal paste could cause overheating.

[newbiebuilder]

You would need a big ol' gap between the CPU and heatsink for it to overheat instantly like that. Just sayin'.

*ROFL. Just noticed this is 20 days old.

[nuz]

If it's not completing POST, then it's probably the motherboard or PSU, if the processor is installed correctly. Bad or incorrectly placed RAM should give you a series of beeps, same with the graphics card. Does the machine have any fans or heatsinks on the motherboard itself? Any swollen electrolytics? A smell of burning PVC might indicate a loose power connection. I spent a couple of weeks troubleshooting a motherboard to find that the mains power cable in the back was loose. It sparked every time the fan motor started and the PSU shut the PC down.

[newbiebuilder]

Let's just keep on beating this horse even though it's clearly seen better days and it's not getting up.