My machine runs perfectly fine with two 512MB sticks of PC2700. When I upgraded to PC3200, the display started blacking in and out and I started getting DRIVER_IRQL_NOT_LESS_OR_EQUAL BSoDs, which sometimes, but not always, mentions these files: nvarm.sys, nv4_disp. When I slow my CPU clock to 166, or put back in the PC2700, the thing runs fine. I have run both PC3200 sticks through Memtest with no errors. I updated my graphics card driver and have a recent motherboard BIOS. I'm stumped... Asus A7N8X Deluxe pcb rev 1.04 Athlon XP 3200+ Barton (400Mhz) 2x Corsair Value Select PC3200 512MB (VS512MB400) BFG GeForce 6600 GT WD Raptor 35GB SATA WD JB 200GB PATA Ultra XConnect PSU 400 watts Thanks for all your help.