I am using a 4x radeon 7000 on it. Do I need a 8x card or is my motherboard faulty?

I believe that the board will work with 4x cards yes. Don't throw the baby out just yet, there seems to be a number of people who have had similar problems to you with this board. What exactly is it doing - eg does it even power up? Get a POST screen or no signal at all? Error beeps? How about the LED by the AGP slot - red or green?

Like San said we some more info.

I powers up, but the monitor says there is no signal.

I tried a pci video card and it doesn't work either

Your monitor plugged in?

yes I checked all the plugs. Well thats what I get from buying a open box item on ebay!

I wouldn't throw it out just yet - if you could get hold of a decent 8x card it would be worth trying it out (worse comes to the worse, you buy a new board and card, find out the mobo works then flog it on ebay again ...).

If as you say it was "open box" from ebay its possible that the BIOS has been setup badly etc - i would have a look at the manual to find out how to reset it (or take the battery out for a bit, i guess that still works?) - also check that any jumpers on the board are in their default position / the right position for your setup.