There are now multiple threads about it. People are asking is there is BIOS fix for 6xxx cards to make them work with Z77 or is it PCI 3?
I bought Z77 AsRock Pro3. It has Z77 chipset with PCIe 3.
The board would POST only if I set PCIe2 to "Gen 1" and with any minimal overclock I had to change CPU voltage (lower it or increase it either one worked).
However AMD catalyst drivers would not recognize 6870 or claim that 6870 is not working right when PCIe2 is "Gen 1".
I build my own computers since AMD 40MHz. Never saw such incompatibility before.
I looked over newegg reviews for many Z77 based motherboards (up to $150).
Eventually someone would write about same kind of problem their graphic card (PCI2 based). Usually motherboard would not POST or is not recognized in Windows.
It is not 6870 that has a problem - lots of other fairly new graphic cards are incompatible too.
Some people tried 3 motherboards already.
Do you have working 6870 in Z77 motherboard? What motherboard is it?
Here is the catch for this board. I build this new pc to replace my old built. So I first build the pc without putting in the Video card to try out the CPU graphics from Intel. Well not too bad but not able to play game in mid setting. Then I bought a ATI 6870 pcie 2.1 to put it into the MB. The MB will not detect it at all, I tried to go to bios to do all the setting change to force to detect PCIE slots. In short I tried every pcie slots and all setting, the only one thing I have not tried is to call customer service of Gigabyte. I bought a pcie 3.0 video card, and it detected it right on first try. So, I got it. This board is not for PCIE 2.1.