go to amd web page see if you can update you mb chipset drivers. if there up to date and your using the blue pci slit it may be the mb chipset dont like newer gpu cards. if you have someone that got a nvidia card you can try and see if they work on your mb.
Try to put another card (could be your old one) to see if it still happens, also check that the pins are correctly attached to the PSU (it happened to me one with a gtx 460) . If all fails try to plug the card into another rig and if it doesn't work either ask for a return.
if your using the black pci slot try the blue one. on most new mb the blue pci slot or white one near the top is the first pci video card slot.if not it the mb chipset being so old it cant handle the new video cards.