okay, I got it now.
Wow. So, the question as you point is: why does it reboot?
When you ran the windows 7 disk, did it give you an option to repair the operating system ?
You tried that and it did not do anything?
That is really strange.
HOW is the windows XP 64 bit operating system doing for you?
Is it stable? Performing well?
I ask because maybe you might want to consider changing to that, which would mean you would need to install the drivers for the mothereboard as well as your folding program and GeForce driver from nVidia.
That might be a pain but ultimately, it may prove helpful.
Reasons why a computer just reboots?
Well, how about an unstable electric supply.
Do you have the computer's hard drive plugged into a un-interruptable Power Supply? This way if you are getting quirky voltages from your utility company or similar things, that would keep it from happening.
It is POSSIBLE that your power supply could be glitching, but it could be some other hardware issue as well like a stick of memory.
Hard to say.
You can eliminate some things by changing them out with others, like the power supply for instance. Trade one with another. See if that solves the problem for the current problem child.
That would tell you a lot. Same with memory modules but that would be last on my list.
I am assuming the heat sink/fan is clean on both the video card as well as the processor?
That could cause some overheating and excessive vibration.
Just some things to look for.
the best,
micro...