The system boots up but the screen is blank?

• One bad lead can cause a computer to continue on a cycle or to shutdown or fail to detect your hard drive .
• Test all leads that attach to your hard drive including electrical extensions IDE,SATA .
• The leads from your "((motherboard to your hard drive))" make sure they have a secure connection and are not faulty or just replace them there probably old and faulty
• Make sure all leads that are attached to your drives dvd\cd 3 1/2 inch floppy have secure connections and are not faulty even the electrical extensions or just replace them they could be faulty a computer needs its connections to continue its cycle and have an end so any faulty leads will end up with a computer error.
• If your computer came with a motherboard disc the drivers could be on it or you might have a dirty graphics card remove the graphics card and clean the socket.