i just got a brand spanking new barton 2500 stepping aqxea retail, i popped it into my msi k7n2, boot up and change fsb to 200 and vcore to 1.75. when i hit save, the computer powered down and i had to remove the atx plug from the board to get it to boot. i tried 166fsb with lax ram timings (8/4/4/4/2.5) and a new psu (sparkle 350w), same thing happened. everything works fine until i change the vcore. the core has no visible cracks or anything, im about to check it right now to be sure. i got a slk-800 with a vantec tornado, so i got enough cooling. i could change the vcore fine with my tbred-a 2200+, and i got that to 148fsb with agressive timings (6/3/3/3/2). i updated to the latest bios and the same thing happened. here are my specs
msi k7k2
barton 2500 retail
corsair megamemory 2000 or whatever, rated at pc3500 and has a black heatsink on it and a kingston hyperx pc3500mhz, i dont use both tho
thermalright slk-800 with a vantec tornado
1x80gb samsung hd
radeon 9800 np flashed to pro
350w sparkle psu
lian li case
16x plextor
onboard nforce2 audio
19'' monitor sony