iknowhowtofixit :
The HD7950 is $320 on Newegg. The GTX 670 is $400 on Newegg (25% more than the HD7950). It can also be safely said that a mildly overclocked HD7950 has no trouble beating the GTX 670 in most games (yes, I'm aware there are exceptions).
The 670 can be overclocked too.....
Looking at the max tested stable overlocks.....
http://www.guru3d.com/article/asus-geforce-gtx-670-directcu-ii-top-review/23
Asus 670TOP Boost Clock is 1137 outta the box .... stable at 1280 Mhz
Asus gets 3DMark Score of 9340 outta the box and
9839 OC'd
http://www.guru3d.com/article/asus-radeon-hd-7970-directcu-ii-review/23
Asus 7970 TOP Core Clock: is 1000 MHz outta the box, stable at 1250 MHz
Asus 7970 gets 3DMark Score of 8280 outta the box and
9680 OC'd
http://www.guru3d.com/article/his-radeon-hd-7950-iceq-turbo-review/23
HIS 7950 IceQ Core Clock: is 900 MHz outta the box, stable at 1125 MHz
HIS 7950 IceQ gets 3DMark Score of 7450 outta the box and
9008 OC'd
http://www.guru3d.com/article/gigabyte-geforce-gtx-660-ti-windforce-oc-review/26
Gigabyte 660 Ti Boost Clock is 1108 outta the box .... stable at 1316 Mhz
Gigabyte 660 Ti gets 3DMark Score of 9340 outta the box and
9559 OC'd
So we see that the 670 overclocked is 2% faster than the more expensive 7970 and that 8% faster than the 7950 at max stable OC's, we also see the 660 Ti being 6% faster than the 7950. The lead increases in actual games.
Using TechPowerUp Game Test Suite (Alan Wake, Batman Arkham City, BF3, BattleForge, Civilization 5, Crysis. Crysis 2, Dragon Age II, Hard Reset, Metro 2033, Stalker CoP, Starcraft 2, Shogun 2, Skyrim, WoW, Diablo II, Max Payne 3, Sniper Elite V2)
The 7950 gets 1348.2 fps, costs $330 and that works out to $0.24 per frame
The 660 Ti gets 1387.4 fps, costs $300 and that works out to $0.22 per frame
Moving to Guru3D's (Hard Reset, COD-MW2, Far Cry 2, ANNO 1404, Metro 2033, ANNO 2070, BFBC2, BF3, Crysis 2, AvP, Lost Planet 2)
GTX 670 TOP costs $430, scores 999 fps at a cost of $0.43 per frame
GTX 670 costs $400, scores 917 fps at a cost of $0.44 per frame
7950 costs $330, scores 746 fps at a cost of $0.44 per frame
7970 costs $420, scores 872 fps at a cost of $0.48 per frame
7970 GHz Edition costs $470, scores 952 fps at a cost of $0.49 per frame
The 670 and the 7950 both finish at identical $0.44 per frame therefore putting them on equal footing in the "bang for the buck" standings but with 170+ fps performance difference, that doesn't make them equal performers.