Great, the passive-aggressive OP comments begin here then (it's inevitable with these type of threads, but it took you longer than usual, at least)...
The burden of proof is on you here, and you've failed to provide any objective replicable method or adequate explanation of your issue beyond the fact that every single PC you tried after your original Windows 7 build just feels "wrong" to you where mouse input is concerned, and we're somehow suppose to know what that is.
We've gone through virtually every conceivable possibility (in the limited expression of this medium), and you've eliminated every single one. Maybe you should temporarily revert to Windows 7 and see if you can replicate the previous mouse response. That, and/or upgrade your motherboard to a newer chipset, even though the odds of that helping are very slim.
Regardless of your issue (and what you experienced on Windows 7), mouse input is never 1:1, even with EPP off. There is a delay between when you swipe and when it is shown on-screen, and that delay can be variable. I perceive that as well, but I know it's a physical limitation of the hardware, so I allow my brain to adapt. If you expect that to be "fixed," it won't be until our hardware can reach near unlimited refresh/frame/polling rates, which, by the time that is possible, it may not even work in those terms.
Whether your issue is beyond that, is something the majority of us can't determine without experiencing it in person at this point (again, we've exhausted all the conventional potential solutions).
Maybe there will be others here with more ideas, but I for one, am out, and we're now just going in conversational circles. Good luck.