be sure its not you monitor, i had that problem, i thought it was the vid card, ram, something i did wrong, but it ended up being my monitor. when i plugged it in it would flick on for like a tenth of a second then nothing.
ASUS A8V Deluxe MOBO rev 2
AMD Athlon64 3500+ 90nm Winchester Core,OC'd @2.6ghz
PNY-Geforce 6800gt, OC@ 420/1.15
2x512MB Corsair Xms Xpert XL pc3200 2-2-2-5
2xWestern Digital Raptors 1-36.7G 1-74G 10,000 RPM HD/ 1x 160gb maxtor
Im water cooled now with swiftech mcw6002 and dangerden maze 4