I just got an asus p8z68-v pro/gen3 with an i7 2700k and an asus HD6950 DCII 2GB
I can only get image from the onboard video (Intel graphics controller). The ATI card cannot even be detected by Windows 7 64bit and Lucid Virtu gives error message No Discrete GPU found (even with multi-monitor enabled in the EFI bios).
Power supply is a corsair GS600. Red led on 6950 is off. I cannot do tests with other hardware at the moment.
I own Sapphire HD 4850 and p8z68-v pro/gen3 fails to detect it
I couldn't get my Sapphire HD 4670 to work either. I should point out I have the standard P8Z68-V Pro, not the gen3.
I also have asus p8z68-v pro/gen3 and asus hd6950 Direct CU2 and experienced the same problem, it's not recognize by the BIOS. I had the VGA light led on the MB. I fixed the problem by setting "primary display" to IGFX in BIOS "Graphics Configuration". At least it works on bios v. 3202 and 3402.
The thing is, the dedicated graphic card (HD 6950) doesn't get initalized until windows 7 welcome screen. It s not a big deal for me As I used 2 displays. One on the IGFX (MB) DVI port and one on HD6950 DVI port, so BIOS and windows logo are displayed on the monitor connected to the MB.
But, I set in windows that the monitor on the HD6950 DVI port is the primary display and everything work fine, games use the HD6950 3d accelartion.