FWIW... I've had mouse issues with Windows 8.1 as well. There have been
documented issues in a number of places. Microsoft says (in that KB article):
This issue occurs because Windows 8.1 introduced changes to mouse input processing for low latency interaction scenarios. Therefore, games respond to mouse inputs differently in Windows 8.1 than in previous versions of Windows.
I think it impacts more than just games, and it probably isn't Nvidia's "fault" but a combination of inexperience with the new changes and bugs in the API. I'm not running an Nvidia card, and I've seen:
* Random, and unexplained mouse tracking issues when crossing monitor boundaries. It works right most of the time, but I have absolutely seen the mouse "jump" vertically at the border of my monitors (by a fair margin), while the monitors are perfectly aligned. I suspected this was due to bugs in DisplayFusion at first, but I was able to replicate it on a clean install of Windows 8.1 without anything else added.
* Other less easy to define mouse tracking issues (cursor "skipping", buttons animating as though they've been clicked, but not activating, and other erratic behavior, particularly in Metro). This is not common, but I have seen it.
* It doesn't play nice with
Logitech's fancy drivers, particularly their smoothscroll support. Metro applications scroll themselves, usually very slowly as though the mouse is sliding (but sometimes very quickly and erratically). Disabling the Logitech smooth scrolling feature globally solves this (and that feature is dumb and adds plugins to all your browsers so good riddance).
* Installing TightVNC's Mirror Driver can be disastrous. I've had this cause Windows to stop responding to mouse input altogether, persisting across reboots. It worked fine for a while after I installed it, and after a reboot, but after it had gone to sleep (when I went to sleep) the next morning my mouse no longer worked. I could open the Device Manager (using VNC and a keyboard to drive, since my mouse wouldn't work), and see the mouse, but unplugging it and replugging it, rebooting, nothing would make it come back. Removing the Mirror Driver fixed it.
The mirror driver worked fine on Windows 8.
* Games have trouble. Some of
these issues have been fixed, but it looks like Microsoft is doing it per-game, custom style somehow. Hard coding in workarounds seems bad and difficult to scale. I'm not sure what is going on here, but it seems kind of widespread.
* Installing
ASUS's Motherboard Suite is fraught with peril. If you install any of their USB3 utilities that come on the disc or are available at their website (unless they've updated them in the past two weeks or so), you are hosed. On next boot, you will have no USB support of any kind (the root hubs fail to load in Device Manager). Windows "otherwise" works fine, but you can't do anything. To get going again, you have to boot using a PS2 device and use that to open the Add/Remove Programs and remove the entire AI Suite (or at least all the components that,
even obliquely, reference USB).
Or, have some kind of remote desktop application installed and set up, of course.
* My ASUS P8Z77-V Deluxe has been particularly troublesome, because it has no PS2 ports. When this happened to me, I was nearly done with my clean install (hours later). Everything was installed. MC was up and running. SageTV was migrated over. Adobe's Creative Suites were installed. I had Macrium installed (but hadn't quite made an image yet, which was dumb, but I was on a roll). Unfortunately, I hadn't installed a VNC server yet and didn't turn on the built-in remote desktop (because I use a VNC server to avoid having the local account logged out when I remote in). I'd also installed TeamViewer but I use that to remote-support my parents and friends, and don't run it all the time as a server, so it wasn't set to launch on bootup.
I was installing the AI Suite because I wanted to apply a bios update to my motherboard, and it was one of the last tasks on my list. Pretty much randomly, I was going to do TightVNC next, which would have saved me if I'd done it in reverse. The plan was to install those two things, then do the BIOS update, and then go to bed. I almost didn't install the USB Boost thing, because motherboard "enhancers" like this are usually crappy. But
Ian Cutress at AnandTech checked out USB 3.0 Boost when it came out and it did make a measurable difference. I didn't know that the changes ASUS made were integrated into 8.1 automatically, and incompatible with the way ASUS was doing it. By the way, it isn't just the USB 3.0 Boost features either. My motherboard also had some USB Power doohickey that let you charge an iPad (give the full power) via your USB ports, which is a useful feature, but that caused my system to be borked too in later testing.
Apparently some people have had success booting to safe mode and removing them. I did not, and still had no mouse or keyboard in Safe Mode. I could have probably beaten it into submission via booting to a command line, but I was going to have to remove half-100 registry keys, none of which I had super-reliable references for, and delete a bunch of files out of system directories. And, of course, the idea of clean installing was to clean up cruft when I'd done "surgery" on the system in the past.
It sucked. I ended up nuking it and starting over.
Sidebar: Booting to safe mode in Windows 8 is kind of a pain in the butt if you can't enable it from within a running, working, booted system (which seems like it defeats the purpose). The pound F8 like a monkey method is now useless. It isn't gone, but they've removed the delay there to make the systems boot quicker, and you need to have ultra-human reflexes to get the timing right between when the BIOS loading finishes, and when booting Windows begins. I tried about 30-40 times, and got nowhere. You can make a recovery key if you have the forethought to do it ahead of time. Unfortunately, I didn't, of course. I managed to make one finally, but that ended up being a hassle because my HTPC's recovery USB didn't work at first because of fiddly EFI vs MBR differences. And, then I get into Safe Mode and it didn't work. Sigh.
Overall, I like Windows 8.1 pretty well. Once you get it sorted out and don't install any "bad software" I've not had many problems (other than the occasional erratic mouse movements, but this is minor and rare). The changes Microsoft made in the input support are quite possibly completely necessary (and long-overdue), or they might have been harebrained and scrambling to fix their High DPI support because of "retina" competitive pressure from Google and Apple. I don't know, but something is different, and it seems like it is fussy with a bunch of software (and some on it's own).