Disconnect all hardware inside the computer (RAM, Optical Drives, any extra Hard Drive's you don't need to boot into OS) and take out all cards except the video card, reboot the computer. See if the BIOS screen appears. If it does then you on to a winner. Turn off the computer and add just the hard drive, reboot, auto detect the drive in the BIOS, see how you get on then keep adding one item at a time.
Anything that'll fix this is worth a try. And this is from personal experience.
Anything that'll fix this is worth a try. And this is from personal experience.