Overclocked to 275, firmware 2.0:
Risk - menus & in-game: 28 fps, very playable!
Vandal Hearts - menus: 28 fps, in-game: 8-11 fps.
Kings Field - menus: 19 fps, in-game: 5-9 fps
All games are .Z compressed with movies and music stripped out. I didn't have much success with underclocking...