Thanks to all, this is exactly what I was looking for. Got another "regular" xfx 5850 coming from the egg and the differences in clock speed is negligible. Looking tpo see what two of these can do in crossfire. I have a 1100 Watt PS, so there should be no issues putting these two to work.
thanks again for all replies
system is
Haf 932 Blue
Phenom II X4 965 BE 125w 4.01 Stable 24*7 OC
16GB Gkill Ripjaws 1600
8o GB Intel SSD - Boot
600 GB Velociraptor - Apps
2 TB WD Green - Storage
Corsair H50
XFX 5850 BE
2 24" Dell 2407WFP's