What is meant by X4 B55 BE? X2 555 BE?
X2 555 will bottleneck those card pretty much even with overclock. I recommend an upgrade to X4 955 or better and a bit of overclock it.
If it's X4 955 BE or better, it'll not be bottlenecked, if it's bottlenecking, you can overclock your CPU and eliminate the bottleneck problem. Good Luck