I have a h8-1234 HP and I purchased a sapphire 7870 radeon to replace the factory card. I upgraded my PSU to a 650watt Antec, hooked up the graphics card turned the power on. The computer seemed to be booting up normally, however, the display is not coming on. I am certain I have enough power to the card, so it might be my motherboard is not sufficient. Any help would be much appreciated.