What is this extreme4 Gen3 combined with Z77? I only see a Z68 Extreme4 Gen 3 or a Z77 Extreme4 listed on their website (I have the later).
First off, did you try an out of the case post? If not, do that. All you need is the motherboard, CPU, RAM and PSU. Connect monitor to onboard video output of your choice. Power up PSU and pretty the power button on the MB.
But, I would like to clarify which board you acutally have. If you do have the Z77 Extreme4, you should be OK, but if you have the Z68 Extreme4 Gen3, you may have a problem as that mother board doesn't support Ivy Bridge until Bios V 2.10. If that is the case, you have a couple options other than returning the board. Contact ASRock so they can send you out a new bios chip that will support your ivy bridge processor, or you can install a sandy bridge processor to boot and update the bios.
The Z77 Extreme 4 supports Ivy bridge natively with the very first bios.
You might add extactly how you have the memory configured as well. I'm guessing it's 2 4GB sticks, if so then they should be installed in the 2nd and 4th slots from the CPU socket.