I started a thread on the 9800XT Vdd mod: http://www.xtremesystems.org/forums/...threadid=20855.
I figured I'd start another thread for the GPU vmod. The PWM controller on the 9800XT is different from the 9800pro, it's the Fairchild FAN5240MTC, http://www.fairchildsemi.com/pf/FA/FAN5240.html. I've just started studying the data sheet, but the interesting thing about this part is that it's original intended application was as a two phase PWM controller for the AMD mobile Athlon and Duron processors. Voltage is supposed to be adjustable from .0.925V to 2.00V, with a 5 bit input for voltage selection. If we're lucky it might be possible to control these directly, although some may be tied directly to ground, which would complicate things.
Anyway, I thought I'd pass on this info so we can get started working out a mod. Hopefully I'll have some time this weekend to work on it.
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