I have a somewhat older pentium 4 computer in my office here that seems to be randomly shutting itself off. When I turn the computer back on, immediately following the POST it says "Press <F4> to run Setup", pressing F4 brings me into the BIOS. I checked the temperatures and it was about 54C which I believe is okay for a P4? When I tried to exit the BIOS it just hung there and I had to turn the PC off. When I turned it back on again, it booted into Windows fine. This only just happened this morning, so I don't have a long enough time period to see if this problem will repeat itself or was just some fluke. I noticed the fan on the power supply is a bit loud, it's always been like that though since the year I've been here. I'm considering replacing it as a precaution and to make the PC quieter as well. Are there any particular tests I should run to check for issues? Or should I just wait and see what happens and replace the power supply?