lozzahh_XD :
you know the 770 is already OC when you buy it so it narrows?
All R9 series cards are very aggressively overclocked. The 7xx series cards have moderate OCs.
For example:
Reference 780: Core Clock = 863
Asus 780 DCII: Core Clock = 889
That's a puny 3% factory OC. The card has no problem at 1089 (26% OC) ... that's 23% headroom.
The reference R9's are already very aggressively overclocked....as such the available headroom is much smaller.
I like the approach .... If for example Asus were to overclock that card to say 990 ..... most peeps would still be content getting it up to 1089 for a 10+% OC. But a certain amount of cards will fail to hold stable at 990 in which case they'd have to deal w/ RMAs..... at 889, they can still let reviewers blab about how far they got it to OC but when someone can't match it, they just gotta say, "well it is only guaranteed for 889". With the aggressive OC, the AMD has to guarantee the advertised speed which is better for that "1 in who knows how many " customer who gets less than he / she expected.