Thanks for all the suggestions. Have had both cards out swapped them and also now only running one crossover ribbon, more on that in a sec. I removed all drivers and now have the latest drivers 8.981.2.0 & catalyst program and the crossfire add on too, out couple of days ago.
I have used Fur Mark 1.9 and get all the specs, core725mhz and mem1000mhz on both and good results scire 4300 with only one ribbon connected even though the manual states two and only get a score of 2900 when both ribbons are on. weird
when crossfire is off, BF3 works great but with it on only last about 2-3mins in game?
All cards running std specs am not overclocking.