what resolution you running?
what shadow texture size you using?
are you using the drivers from the CD or XFX website? which is currently 11.5 for XFX cards ( CCC & display driver )
what CPU, Memory & OS are you using ( can it push the card??? )
I also have an XFX card, except it is the 6870 1 Gig GDDR5 version with 2 cooling fans...... I just updated my drivers with the AMD/ATI 11.6 reference drivers and got better performance than I got with the 11.5's..... that XFX loaded from their support website
TC