can you get display from the basic inbuilt graphics? can you get display if you use an old video card? have you tried using one stick of ram to see if any have gone faulty?
if its a powered card are the cables plugged in correctly? tried reseating your ram?
Deleting the display drivers should not stop you from seeing the BIOS boot screen or the Windows boot screen. Is the computer booting at all? do you hear the sign on beep? do you hear the normal windows hard disk start activity?