actually, its a 2900 pro that i flashed to a full xt and i'm running it at 840 core and 890 memory. the way i got the cpu to clock that high is by enabling the "cpu overvolt" option. it overvolts the cpu by .2v and enables 8 phase power (stock is 4 phase) which made my overclock a lot more stable. so even though the cpu voltage option reads 1.45 volts, its actually 1.65v cuz of the overvolt optioin. (if you do it, do it at your own risk obviously). try setting your cpu voltage to 1.2V and enable the cpu overvolt option, then see where that takes you. i stumbled across that little bit of information by dumb luck and it worked. without that option enabled, my max oc is only 2.73 before it gets unstable.
also, roll your drivers back to 8.2 and make another run. your score should go up.
ditch the ultra x2 and the thermaltake gpu power supply if you can (i have both of them too). the thermaltake cant really power the 2900pro's and xt's very well...i'm running my computer off my corsair 520W and i'm now running my video card off my old ultra x2 550 (which is running 24/7 cuz its hotwired.. hehe). for some reason, even with the card at stock, my score is still like 9800 or so. i dont know why...
. i think 3dmark06 is very cpu bound.