This is almost embarrassing to admit but I finished Cryostasis, Metro 2033, and most of The Saboteur with my 4890 core fixed at 500MHz. The entire time I was complaining to myself how slow everything was yet the thought of a problem never crossed my mind. Not sure how long this was an issue, I'd imagine at least the entire time I had the 10.3 previews installed. An uninstall, driver sweep, and reinstall of Catalyst 10.5 fixed the problem. 