I have a store-brand P4, 3Ghz that was working swimmingly until about a week ago when it started rebooting after every half hour or so. That quickly increased to every few minutes and now, I can't even start loading my OS (winXP.) Here's what I've done so far.
* Removed all hardware devices (incl CD-roms) except the hard-drive
* Tried a different harddrive
* Installed a new power supply
* Swapped around my two 512M memory sticks, running on one or the other in both slots. (One stick came with computer, the other was purchased about a month or two ago.)
* Wiped the hd and tried re-installing windows. It starts, but then stops. Can't get past the "installing devices" portion
* Tried a different OS (Ubuntu linux)
* Tried a different OS (Debian linux)
* Tried various different BIOS setting changes (including changing HD to LARGE and resetting to fail-safe defaults)
BTW: The computer does not start its rebooting routine, unless the OS is trying to load or is being installed.
... that is to say it will remain on indefinitely on the BIOS screen -- or the occasional BSOD, which by the way says something like DRIVER_IRQL_NOT_LESS_OR_EQUAL
All three of my fans (CPU, back of machine and power supply) are working properly.
All of this leads me to the conclusion that it's probably a hardware problem and that it's either the motherboard or the CPU (since nothing else is connected.) How can I figure out which one, without buying a new CPU or motherboard. If it's the motherboard, I don't want to have buy a second CPU.
Any help would be greatly, GREATLY appreciated.