I'd keep your current CPU and just get a HD6950/HD6970 instead. I would suggest that you skip at least 1 generation before upgrading your CPU so that you have performance that you can actually feel. The SB may be fast but definitely the upcoming Haswell would be even faster. Save the money from getting a better motherboard with 2 PCIE 16x. A single powerful GPU is better IMHO as you don't have to worry too much about scaling issues, game support for multi GPU, power consumption, heat and noise.