I would probably avoid the Vapor-X if you can. It has less than adequate cooling on the VRM's. This is just based on the 7950, I am not completely sure if it affects the 7970 as well, but most likely does. A Dual X sapphire is much better.
guyz is it 7970 vapourX or a MSi gtx 680 oc edition??
Probably should point out what your friend, not yourself is running. How many monitor's is he using? How high of a resolution? What is he using it for?
Please read the thread of responses you've been given. The answer, is NEITHER.
Only one had half-vouched for the GTX680 since they recomended a 7970 as well while there are far more people vouching for the 7970, so that is out.
One post cited concerns about cooling issues with the VRAM, so that's a STRIKE ONE! on your pick of a 7970
One post cited it's a waste of money for a 6GB card except at serious gaming with 3 monitors in eyefinity, unless you post more details on your friends usage, thats a STRIKE TWO!
Every post in favor of the 7970 made a 3GB recomendation AND a different brand/model of the 7970 so STRIKE 3!
Both of your choices struck out. If you insist on helping your friend, give up on insisting people make a choice on your two preferences when they feel bothered enough to make every recommendation but your choices.
Get a DEVIL 13 edition HD7970 from Powercolour which is 3GB
it is better than the Vapor X coming from Sapphire
There is no question about going for Gtx 680
no such thing as a DEVIL 13 edition hd 7970 however there is a 7990 with dual gpu (7970s) which is like $1000 so no that is way out of the question..
To be honest it comes down which one do you want more the gtx 680? which is pretty much more expensive than all 7970's.. but it may be better in some ways such as phsyX and other features that are nvidia exclusive..
It comes down which one do you prefer, yes in some cases the 7970 can out perform the 680 once overclock BUT the 680 can dominate it when its overclocked..
If you want bang for buck get the sapphire 7970 vapour-X 3GB if you're getting more monitors in the future get the 6GB.
If you want More performance get the msi 680 lightning 2GB