HI all, first all just a bit of background, I currently have one 6870 running three 24" LCD's at 5760x1080 to play racing sims like iRacing, race series, F1 and others. The main sim i run is iRacing and get a solid 80 FPS on max settings with 4xAA, the other sims are not as optimized for three screens and struggle a bit around the 40FPS mark.
Now I have a spare £100 or so and have three options :
Sell my current 6870 for £80 - £100 and buy a MSI 6970 2gb Lightning for £160 - 180 ... or
Sell my current 6870 for £80 - £100 and buy a 7870 for £190 - £200
buy a second 6870 for $80 - £100 and go crossfire.
my system is :
ocz modxstream pro 600w
Im leaning towards the 7870 but am not sure if more vram is better for eyefinity or crossfire power.
I personally think that you should definitely sell up, and get the 7870. Crossfire has it's issues you may get better performance out of the single 7870 than two 6870's. Also, it allows you to get another 7870 in the future if the funds are available.
More Vram is better for the eyefinity large resolution. CF doesn't give you a 100% boost, anywhere from 20-70% usually but depends on the game. Some games don't like CF at all. It's more heat, more power in your PC running CF. Getting a 7xxx series card gives you a bit newer technology and will run everything off 1 card.