Computer Restart Issue

[Micheal]

Dear Community,

A friend dropped off his PC for me to repair stating that it randomly would reboot itself, or at times, not boot up at all. I've run a few tests and I am unable to find a solution to the problem nor do I really know whats wrong. If you could help, it would be appreciated.

I cleaned the pc completely the day he dropped it off as it was filled with heavy soil dust and I wanted to be sure it wasn't an overheating problem. I reseated all the wire connections and removed/cleaned the GPU and Memory modules before doing any booting. When I did boot it, it booted fine, loaded the OS and sat at desktop for several minutes with no issue. I left it running to see if built up heat was an issue and left it for about 2 hours. I noticed after a while, it just shut off and started rebooting. No warning windows, no evidence of a crash, it just immediatly went from desktop to the POST screen. After rebooting itself 2-3 times, it started to fail loading the OS and eventually would restart mid-POST.

I ran several tests removing or replacing components to try and narrow down the issue.
1. I switch out the 350w PS for a 1250w PS, and no change.
2. I removed the DVD-drive from the pc, no change
3. I tried combinations of just one Mem Module, in either slot. I tried the other Mem Module, in either slot. No variation of memory fixed the problem.
4. I removed the HDD and hooked up a new one, figuring I'd reinstall the OS while I waited for the failure. No change, it just failed randomly during POST or OS installation.
5. I removed the GPU completely, no change.


At this point, the only thing constant among all the tests was the inability for me to switch out the CPU or Motherboard, and I don't have any knowledge on what to do from here. If you have any suggestions for me to try or if you know what the issue is, let me know.

Micheal

PS: Certain times when it failed, it would only reboot with the PS running and the CPU fan running. The GPU card fan was not running, there would be no video out, and no noise from the HDD that would signal it doing it's booting. These types of failure required a hard shut off of the switch on the PS.

[Micheal]

So I should check for tilted or leaking capacitors? Other than replacing the motherboard, is there a way to bypass damaged Caps or to replace them?

[raghini]

So I should check for tilted or leaking capacitors? Other than replacing the motherboard, is there a way to bypass damaged Caps or to replace them?

Yes you can check out the capacitor very well and if you find any to be suspicious then you can get it repaired from the manufacturer but then you will have to confirm it out if they repair the capacitor or not, if the computer is not that old then there are possible chances of getting it repaired.