Gigabyte is ok... but don't expect to mine with them in a case. These guys need aftermarket cooling on the backside or extender cables so they don't cook whatever happens to be near them.
I run a pair of them, and an Asus 7850 in a single case. 7950 are in top and middle slots, the 7850 is bottom. The top card does run about 10C hotter than the middle one, probably because it's drawing heat off the back of the middle card.
The 7850's cooler sucks (single fan DirectCU II), and it runs hottest, despite having the best ventilation. And it gives crap performance. It's rubbish.