Been having random rebooting issues with my now prehistoric PC, of about 7years.

Athlon XP3200 with 2Gig of some PC<value> ram(ie. not DDR of any kind).
Lots of fans to keep things cool, and regular vacuum of the internals of the box for efficient airflow. Pretty cool Antec case with Antec PSU(with tons of power in reserve for this low power system) so the PSU shouldn't be over stressed.

But I get random rebooting problems.
I suppose it's about time I updated this box as it's so old, but it (used to) runs so well.
Would love to have a new uber fast CPU and all that to cut processing times down by 0.0045s or so, but I don't mind the glacial pace of this system.

First thing I thought of was the PSU may be dying, as the random rebooting is preceded by a faint click sound, as though the system is powering down for a micro second. I hear this faint click regularly, and I'm assuming that sometimes the 'power failure' isn't long enough to cause the PC to reboot, as it doesn't always reboot with the faint click sound.
But when it does reboot, the faint click is definitely heard the moment before the reboot, There is a very quick slow down of the fans.. heard but not seen.

This rebooting can happen anywhere from approx 1hour intervals(noted) to longer(not noted) as the PC can be just left standing with no windows open, and not doing any processing, and I come back to find the login prompt(ie. it's rebooted).

I'm 99.9% sure it's not software related.. and now with the 3times more powerful PSU than the system needs(measuring current not just absolute power of the PSU) I had it sitting and then working and then sitting again, and after it;s first two hours of operation on the new PSU it rebooted again, with the same faint click sound and the microsecond slowing down of fans just before reboot. No BSOD, just a restart. never any hdd errors or windows coming back and asking to boot into safe mode.. just a straight up reboot.

I'm now stuck for ideas. Mainboard may have a fault(how to test/check) all system parameters as displayed by the BIOS and MBM5 look ok.

I'm fairly sure than this is not software related.. if it was how to check. Found some error log files, that don't list any errors for this issue, and the last set of entries are for ViewNX a few weeks back which wouldn't work on my system due to some dll error.. back in Feb.

The rebooting was almost predictable at every hour for a while, and then changed it's mind to maybe every 1.5 hours of operation.. could run for up to and beyond 3-4hours at total idle with just the desktop displaying at which point I gave up counting the interval... so it's random.. but predicatble on in that I know it can happen at any point.

makes backing up HDD's images and so forth hard to do, as the last thing I want is possible corruption to data.

Processing images and keeping the CPU under load for any length of time makes no difference to the rebooting either. Just did a batch job of some images with the CPU at full load and no reboot.

I think it's definitely power issues somewhere.. but where?

Maybe a new motherboard, CPU and ram is the way to go now.

Wasting of money isn't an issue, as all the parts I'm getting(or will get) will go to a new PC system in the long run.
(which begs a new question... AMD or Intel).
Intel seems to have a slight speed advantage, but the more than $200 saving in going with the AMD hardware makes for a very compelling argument


other thoughts?