Between the two: ASRock Z68 Extreme7 Gen3 and ASRock Fatal1ty Z68 Professional Gen3
The main differences are on PCIE lane width and number of PCIE Gen3 slot
ASRock Z68 Extreme7 Gen3 has a single Gen3 PCIE but with nVidia nf200 chip therefore it supports
single video card at x16 (Gen2 speed with Sandy Bridge or Gen3 speed with Ivy Bridge plus 3.0 video card)
dual video cards at x16, x16 (Gen2 speed only)
triple video cards at x16,x8,x8 (Gen2 speed only)
vs
ASRock Fatal1ty Z68 Professional Gen3 has two Gen3 PCIE but without nVidia nf200 therefore it supports
single video card at x16 (Gen2 speed with Sandy Bridge or Gen3 speed with Ivy Bridge plus 3.0 video card)
dual video cards at x8, x8 (Gen2 speed with Sandy Bridge or Gen3 speed with Ivy Bridge plus 3.0 video card)
triple video cards at x8,x8,x4 (Gen2 speed only and the 3rd card at x4 is useless)
If you plan to use triple SLI or Crossfire now, go with ASRock Z68 Extreme7 Gen3, but it is less future proof
since it has only one PCIE Gen3 slot, you won't be able to achieve SLI or Crossfire in Gen3 speed even with Ivy Bridge.
If you plan to use only dual video card (SLI or Crossfire), go with ASRock Fatal1ty Z68 Professional Gen3. In
the future, you could upgrade with Ivy Bridge and run dual 3.0 video cards at Gen3 speed. But triple SLI or Crossfire
is useless since the 3rd PCIE slot is only at x4.
So it all depends on how many video cards you plan to use on these boards.
http://www.hardwareheaven.com/reviews/1232/pg1/asrock-z68-fatal1ty-gen3-motherboard-review-introduction.html
This review shows that the ASRock Fatal1ty Z68 Professional Gen3 run fine with two gtx590. I think it is also same
for ASRock Z68 Extreme7 Gen3. I doubt a lot of people plan to use two gtx590 or two hd6990 ...