Hello! What might sound strange is that my system did not seem to have certain problem before I tried out Windows 10 (on SSD (which I have already formatted afterwards)). I am running Windows 7 x64 and in game utilizing non-raw mouse input (non-steam CS 1.6) I get occasional jumps while moving mouse as mouse sensitivity would get a lot faster than it should be.
My current mouse is Logitech G400s, thought it was faulty and connected also Logitech's mouse G9x (disconnected G400s) - same problem. Have tried other USB ports, with, without drivers.... Installed Windows 7 x64 on SSD still the problem persists, however, setting mouse to 125 Hz on newer installation of Windows seems to be more fluid than older one which seems to be freezing for some ms few times a second perhaps which is not so obvious on newer installation.
I have even downgraded my BIOS (in case Windows 10 managed to plant something ~there~, but would that actually help (OC profiles are persistant, so it seems some data is not affected by flashing BIOS that is found on motherboard)).
TL;DR – tried out Windows 10, mouse started jumping sometimes in game while moving it even though running other Windows installations. Could it be that Windows 10 messed up with BIOS? Not sure if security related, but perhaps somebody is interested in phenomenons (or not so phenomenons, oh well)...