RE: Precision M4800 : Input lag at log in, Switchable graphics not functioning, GPU fan "chirping" when it starts up.
I have the same issue as you and can sympathize. I have noticed that the most recent windows 7 and windows 10 ATI drivers have been removed. Could this be a sign that they are finally working on a new set of drivers. Hopefully these will fix the graphics issues I and many people are having.