I think the overclocked GTX660TI cards are pointless
TBH especially with the gimped memory bus which in the long term is not a good bet
IMHO for around £240 to £270.
I am getting a serious 8800GT 256MB vibe with this card.
The ones with 1GHZ core are around £260 to £270 which is only £20 to £30 less than a GTX670 which can be had for £280 to £290. In the US the cards are much cheaper relative to the others - more price gouging in the UK.
The price difference is not massive compared to the GTX670,and you forget the HD7950 3GB is underclocked anyway:
http://hwbot.org/hardware/videocard/radeon_hd_7950/
519 cards submitted with a 1166MHZ average overclock. Even a crappy HD7950 will hit 1GHZ at least.
If you don't want to overclock,a cheap GTX670 makes more sense
IMHO and if you do I consider the HD7950 a better choice than a GTX660 if you get one for under £250(although the same can be said to a lesser degree about overclocking the GTX670). Considering that there is meant to be a price cut on the HD7950 soon,it looks to be a more balanced choice
IMHO. Also most of the HD7950 3GB cards are going to start shipping with the core boost BIOS anyway(you can apply it to older reference cards too).