Sapphire has about 10 versions of their own... Gigabyte has about 5... Asus has only 1, powercolor has about another 10.
The differences can be fairly big, so check clock speeds, before making any kind of purchase.
<A HREF="http://forums.extremeoverclocking.com/myrig.php?do=view&id=17301" target="_new">My PC</A>