Did you uninstall the drivers from your 6850 first?
I didn't. I've installed the most up-to-date drivers for the new card. I still need to uninstall the drivers for the old card?
It could be the problem. If i were you i would uninstall both and give your new card a fresh install. Hope this works for you.
That did the trick, I'm up to 3877 now on the 3D test (687 on the 2D).
For the record, I used the Guru3D Display Driver Uninstaller tool in safe mode, removed the AMD drivers then restarted, removed the Nvidia drivers then restarted, then reinstalled the Nvidia driver from the installation CD. I'm going to update to the most recent driver now and hopefully everything will still be good.