as of now iam running 2 sapphire 4870s in cxfire, i want to accurie a 4870 x2. will i be able to run this setup in crossfire, one single 4870 bridged to the 4870x2, and what sort of preformance increase will i see over the cxfire im now running? or mabey wiser to wait for the 4890x2, any thoughts?