How much memory you got, also, assuming you're playing with each client windowed you're unlikely to be using xfire anyway.
I played with 5 wow windows open but I go with main window top gfx options, other 4 windows smaller and capped at 15fps, that way I can see whats going on but not waste options on them. However they all run fine at higher speeds without the caps on, stuck at 4gb at the moment, some stuff died in my older ddr2 setup so bought new stuff and with the memory pricing 8gb cost well over twice what I paid for 8GB ddr2, with only 4GB its the memory limitation that stops me adding graphical options/resolution/shader quality to the other clients, nothing else. The main client will use 800MB or so IIRC< and 5x that + windows, firefox and several other things open means thats a no go, with graphical options at minimum the other clients are around 350mb each I think.
Either way, a 6770 should be, around 5850-5870 performance, a 6870 will NOT be double that performance in the same way the 5870 was over the 5770, it will be closer to 30-40% faster at a guess.
Theres no chance in hell a 6870 will be £400, that would to make any sense place a 6850 at £300 and a 6970 at £600 minimum, thats simply not going to happen.
The 4870 had no viable competition at £180 when it launched, yet thats where it launched, the 5870 had no viable competition AT ALL at ANY price point, and thats where it launched. There was literally hands down nothing available that could touch a 5970 yet its rrp was £440, so why, for the 3rd gen/time in a row with zero competition would things be different this time around? Answer, it won't be.
Not a huge performance gain but 33% added cost, AMD and Nvidia(when they can) want to price cards to the point where as many people as possible can afford to upgrade to them, at £400, it will make LESS profit on teh 6870 than at £300, not per card, but they'll sell exponentially more cards which means, more profit. Sell 50k £400 cards with £150 profit , or 500k £300 cards with £100 profit. Thats 7.5mil vs 50mil, volume beats higher margin, massively, and easily and has been the ENTIRE reason for AMD's surging sales, increase in market share, increase in profitability, increase in uptake in prebuilt computers which leads to an increase in AMD CPU/mobo sales as those guys go with an AMD gpu and so the platform is a cheap option.
So the very key thing AMD has built all its success on, selling more cheaper gpu's will just go out the window, not likely.
