Random reboots after HW upgrade

[neomage]

Hey, i was wondering if any of u linux gurus out there could help me with a problem i was having. I've been using linux for about 2 years now, and am pretty good with it, so u dont have 2 hold my hand for really simple stuff. My system was an athlon XP 1900+ on a Asus A7v266E (Via kt266 chipset) motherboard, and a Geforce 3 ti 200 . about a week ago, I was able to got an athlon xp 2500+, a Mach Motherboard (no model number on it), with the via kt333 chipset, and a Radeon 9000 Pro w/ 128 megs of memory (got it drt cheap, so decided 2 upgrade, normally i would not bother with such a small performance increase).

Anyways, after installing the components, win2k was blue screening on me @ boot, and I didnt really wanna deal w/ it. i had been meaning 2 upgrade to XP since SP1 came out, and this gave me an excuse to (before the upgrade I had backed up all really important stuff 2 a second NTFS partition, so i could just format the first, and not lose data). Anyways, i installed XP SP1 slipstreamed and all was good. However, during the install, XP overwrote my MBR, and in the process GRUB. (I hadnt booted into linux since the hw upgrade).

To fix the problem I just used my gentoo livecd to boot, remounted all my linux partitions, and reinstalled grub onto the MBR. (I had gentoo linux w/ the 2.4.20 kernel). However while i booted w/ the livecd, the system would reboot at approximately 5 minute intervals for no apparent reason. After this happened twice, i got fast enough so i could fix grub in about 3 minutes. I figured it was strange, but maybe it was just a problem w/ the livecd.

I then booted into my real gentoo installation, and everything was how it should be. However at random intervals, while i'm in linux, the system just reboots, just like if i had pressed the reset switch on the case. The system never stays up for more than 30 minutes, and usually under 15.

My first reaction was that i had a HW problem. like my powersupply (300W) wasnt sufficient, or that my cpu was overheating. however, when I am in windows i experience no problems at all. My cpu is at a constant temp of about 50C-55C, and no matter wat i'm doing, it doesnt crash like in linux.

My second thought was that i had something in my kernel, or one of the modules i was loading, that didnt agree w/ my Hardware, but since the same thing happened when i booted off the livecd, it rules that out. besides, my system isnt staying up long enough for me to recompile the kernel.

I'm completely stumped, i really dont wanna format, i've spent the better part of the last 6 months getting gentoo just the way i like it. I dont really noe wat logs, or info u guys would need to diagnose this problem, so jsut tell me wat u need and ill post it. Thanks for ur time for looking at this at least, and sry for having it so long, i just didnt wanna leave out anythin i knew.

[loxety]

have you tried just booting into a live cd and leave it for a while.. see if it reboots then?