Ryan has an HP computer and it came up with a black screen. He tried to swap out the power supply, video card, removed all the USB peripherals, replaced the CMOS battery, and still has a black screen. He can hear the power supply running, and the fans are spinning up. Leo suspects it may be just a bad motherboard. Since Ryan has done all the easy stuff first, and then tried replacing peripherals, that only leads to the main motherboard. He should also listen for POST codes to see if the machine is letting him know something is wrong. It will tell him with beeps and that could indicate what the problem is. The power supply could be underpowered also.