Greetings,
I'd like to share something I discovered.
If, after a operating system reinstall or since a long time or a few games, you experience FPS drops, mini-freezes or crashs to desktop, it might happen that with the newest catalysts your "PoolusageMaximum" wasn't set up right in the registery.
This fixed HL2 from 15fps to 80/100fps, mass effect up to 40 fps and WoW gave me a 30 fps in dalaran (AKA latency city) and took away the freezes I had every 5 seconds in freelancer once I was within a 2k range of a battle.