As a side note, I tried to run a 7850, a 7970, and a 5450 in the Asus board, and it wouldn't work right. I pulled the 5450 and it worked ok, but the 7850 died completely after a few weeks. Computer one day refused to boot, pulled all the cards except the 7970 and it booted. Put just the 7870 and it refused to boot into windows. I returned the fried 7850... it could have been a bad card to start with. But it could also have been the board fried it.
I think this Asus board is sensitive to higher power video cards. It seems to work fine with a 7970 and two FirePro 2460's, and I might add a third FirePro 2270 to it and it probably would run fine with that in there too. The Gigabyte might handle more high power cards at once than the Asus.