I've tested with 4 different mice that all have no acceleration whatsoever, same exact thing occurs: CM Spawn, Deathadder, Zowie AM, G400 Mouse Pads: QCK Heavy, Razer Goliathus, Artisan Hein, Desk itself What I see in game: I get the same amount of negative acceleration with every mouse. The issue will occur even with extremely slow swipes, so i doubt it's that i'm hitting max tracking on my mice. Moving my mice in a straight line across my pad will make my character in game look slightly to the ground as he pans to the side which lead me to believe it was an interrupt related problem. I haven't been able to test a mouse over ps/2, but i have tested all my mice on a second PC where they all work flawlessly. There seems to be something wrong with motherboard itself as the issue persists even when re-installing windows and a BIOS update. What I've tried so far: 1. Deleting / re-installing drivers 2. Re-installing the MarkC Fix 3. Closing all background programs while i game 4. Different video drivers 5. Making sure EPP is off and Windows is at 6/11 with 100% scaling 6. Re-installing my games 7. Unplugging any other device aside from my mouse while testing in game 8. Re-formatting to a completely fresh install 9. Trying different ports / disabling USB 3 and legacy in BIOS 10. BIOS flash 11. Disabling all power saving features / c steps 12. Stress testing my hardware (minus motherboard) 13. Checked hardware for any loose cables 14. Tried my SSD by itself and on every sata port 15. Installed Win 7 to HDD 16. Removing GPU and running on onboard video 17. Used one stick of RAM at a time 18. And lastly checking to see if my issue was DPC related by posting my info here Everything minus the mouse movement in game works. I tried changing IRQ to see if it was a conflict issue, but Windows doesn't allow me to reassign them unless it says there's an issue. I have no idea what else to do except to RMA the board, it worked fine for a short time then this issue came up out of nowhere.