When ATI tool worked with my 8800GTX i had separate 2D/3D clocks, which changed automatically when 3D mode was detected. 2D mode temp was under 49 (sensor stuck at 49), 3D mode at 70 degrees. core/mem 250/500 @ 2D, 600/800 @ 3D.
Doesn't ATI tool work with the new 4800 series?