Alienware Aurora R4-no power following videocard replacement

I have an Alienware Aurora R4 with the latest bios (11). After installing a new ASUS GTX970 videocard the videocard shows a clear light, however the computer will not start. It appears that the power supply is not sending any power to the machine. When the video card is removed and the original card, a GTX 660 is reinstalled the computer boots up normally. This problem is present in both R4s that I own. To determine if the card was bad, I next used a GTX 1060 with the same results. Any help in resolving this power up issue would greatly appreciated.