Yeah the one plus side to the Gigabyte cards is they never seem to throttle and clock the highest. Of course they use like 10-15% more power then all the other cards, so...
As I said, my Zotac card start to mine quark at 15.5 mhash, and then it trottles and fall down to 13.5-14. My gigabyte is stable at 17MHASH. 3,5 MHASH bether.
The zotac card is much smaller and heats up faster.
I have an msi 970 that is more stable than the others, but still it starts at 16.5 and goes down to 16 after a while. Well, I may get a gigabyte or just wait for the winter ;-)