I have just put together a system with an Asrock x79 extreme mobo, getting power to all of the fans, including video card, and no video whether its DVI, HDMI, or VGA. About to test without the video card, and then I am going to slap my old 4850 in to determine whether its the new HIS 7850. Any help is much appreciated.
Can you tell us if there is any beeps from the motherboard speaker, if you have one?
If you don't, I suggest you go and buy one to test if your computer is POSTing.
I had the same exact issue, turns out it wasn't the GPU at all. No video could be because of RAM, CPU, Power Supply, or the motherboard like I had.
You motherboard has troubleshooting lights on the front of it. When you turn on your computer look at the bottom right of your motherboard and you should see a error code. When you see the code, look that code up in the motherboard's manual and it will (Usually) tell you the problem.