Deus Gladiorum said:
The hierarchy goes:
GTX 760 < Radeon HD 7970 < Radeon HD 7970 GHz Edition < R9 280X < GTX 770
More like this:
GTX 760 < HD 7970 < R9 280X < HD 7970 GHz Ed =< GTX 770
The R9 280X has lower clocks than the 7970 GHz Edition, so actually slightly slower. Nothing that really matters since vendors will throw in factory overclocks and people can overclock as well.