sounds tupid but alot of times, its the simplest things that bite you in the butt the longest. With the computer turned off, hold down the insert key. This is bypass the bios settings. If it boots, you know its something in the Bios. Also, have you tried the new video card on another machine. You also will definitley need to turn off the onboard VGA before attempting to insert the new card. Another possibilty would be the previous drivers are conflicting with the new card. Hope some of that helps.