Ive got a A-open ax6bc main bord and a celron 333a (slot) , I managed to run the chip at 500 mhz once ,but when i reset it the system went back to default speed. So i went back to 375 on a 75 mhz fsb. about 3 weeks later i had the system lock up when running some 3d application in windows, when I reset the system Nothing happened ! I cant tell weather the chip or the main bord is dead. I'me out of ideas on why.