Odd stuttering when in games

by Fumples - 2/5/13 5:22 PM

My specs are as follows:
AMD Phenom(tm) II X6 1035T Processor (6CPUs), ~2.6GHz
AMD Radeon HD 6800
400GB 7200RPM HDD

My computer has run pretty well for awhile now. Over the past months it hasn't gotten progressively slower or anything, but as of late I've been trying some newer games with higher specifications (Natural Selection 2, Firefall Closed Beta are examples), and I've been having an extremely odd stuttering issue that makes the games unplayable.

When I'm in game, my computer does NOT stutter when I'm standing still. In fact, my framerate is pretty good. Not amazing, but consistently above 30FPS. If I run forwards, it's fine. Backwards, fine, Side to side is fine as well. BUT, the second I start moving my mouse to rotate my character around quickly, my game will stutter and turn into a slideshow, as if it's taking awhile to load the graphics behind me or in front of me. I CAN move my mouse slowly and turn around that way without it stuttering, but the second I start moving my mouse quickly it devolves into a slideshow.

One VERY odd remedy to this issue is that whenever somebody is desktop sharing with me through Teamviewer, the stuttering seems to subside almost entirely for the time that we're connected. But the second he disconnects and it tabs me out of game, and I click back in, the stuttering starts up again.

I have attempted the following:
Swap out GPU
Running apps in compatibility mode / administrator
Adjusted process priorities
Updated GPU drivers
Updated / messed around with audio drivers
Reinstalled DirectX + other components
Memory diagnostics

I have also shut off all sounds and listened for any abnormal sounds coming from my HDD, and nothing. Just spinning and air. Whenever I'm in game my CPU usage is usually almost maxed.

if ANYONE knows what this possibly could be, PLEASE let me know. I have never EVER been this stumped on an issue in my 10+ years of working with computers.