GPU access with I2C bus

[Der_Unwissende]

Well, you might study some basic concepts, something like the advantages of abstraction-layers (e.g. the hw-abstraction-layer), of course you should also get information about how to access hw-directly on a windows-system (driver programming, wdk, ddk, ...)

And maybe you should also have a look at the website of RivaTuner, some ATI graphic adapters are supported as well.