Installing radeon hd 2400 pro

Verify that your Power Supply meets the requirements of the video card. Some Video Cards require a 400 Watt Video card. In some cases its always good to go higher than that, depending on how many devices are in your computer.

How old is your power supply? Some power supply's over time will not produce the same amount of wattage when it was new.

Is it possible for you to try the video card on another computer? It could have arrived DOA. In which case you may need to return it.

Good Luck