VIA has yet to announce any product called "KT333a" I think maybe you are refering to "KT333", no?
Unfortunately the core voltage supplied to GPU can not be adjusted by the motherboard. Increasing the voltage supplied to the GPU requires whipping out the old soldering iron and setting to work on the graphics card. The
Vagp that is adjusted on the motherboard has to do with AGP i/o not the GPU core.
Hope you find this small sample my mad rambling helpful
