I have same problem whit my Asus P8Z68-V Pro. I have tried 1000 solutions on internet. Last choise I think will do it is: Change my "power supply". (as I tough all along)
Its only a 620W power supply. And my Asus GTX 560 1G card minimum Req is 500W, so think thats it.
But whats strange is:
Card worked at start, first times I restarded my computer. Then it suddenly wont work anymore.
Total blackness from I start my computer. Only integrated intel card works.
And I install another, even more new drivers from Asus.com. Wont work now either.
I restart and switch slots inside computer etc.
And suddenly it works during Bios and Dos mode. And becomes blackness when windows log in screen arrives.
So it works now and then, but mostly not. So I need to buy new Power Supply =) Got to be it. Check that out my friend.
And yes, both 6pin cable is in. Card gets 2 green lights from 2 orange lights when I do. So that works. And both fans works to.
Bios is PCIe/ ..... etc...all is correct exept Power Supply.
And now I formated PC, and installed Windows 7 Ultimate. Still blackness.
But now I cant even install graphic drivers anymore after I done windows 7 install. Had Vista before. So thats a new problem
How to fix that, I dont know?? And yes, I downloaded new drivers for windows 7 32bit
Said it cannot find any graphic card to support or something. Even its working and plugged in. Perhaps it will be auto detect when I get new Power Supply
Cheers, Tommy M