ATI (now AMD) don't bother updating drivers and supporting older games, mostly they try and support whatever mainstream apps are used at the time. I got a lot of games from late 90s/early 2000s that need Nvidia cards to run. I had an ATI 2900XT and a HD 5770, trust me their support for old obscure games isn't good.
This might help you out.
Just set power management mode from there, shouldnt be too hard to figure out how.
Edited by Kand - 4/27/11 at 7:03am