UPDATE:
Interestingly I had a play with some Nvidia control panel settings to lower graphical quality and then ran Afterburner to see what the stats were saying...On a lower quality setup in a 500 man siege I was getting 68fps in max quality with fairly high gpu usage.
I then turned my Nvidia settings to application controlled and had everything maxed out in the same siege....as predicable my fps was about 5-10 lower but my cpu and gpu usage was only at 60%?
Can I not get more frames out of my setup? Is this an optimisation thing? RAM appears to be running at 8.5gb.