Stuttering is the best word I can think of to describe what I'm experiencing. Happening on the desktop, during video playback, audio playback, games, everything. I'll go into more detail below, but note that this is a pretty new fresh Windows install so it's not loaded up with a ton o software yet. Alright, it all started yesterday when my GF was over and we were watching a video in Media Player Classic - Home Cinema with the Combined Community Codec Pack. Every few minutes the video would kinda jump and the audio would stutter really bad for up to about ten seconds at a time. My initial reaction was that it was just a bad file, but it happened with the next couple files too. So I think "OK, something is up with MPC." Now, here's the interesting part: I closed MPC and just put some music on in foobar2000 and that starts stuttering too. So I rebooted and now my whole PC is stuttering, even just simple mouse movements make the cursor jump around and I'm having a hard time typing because key-presses are getting skipped when it stutters so I have to go back and fix it. Alright, this is pissing me off, but this is a new build so maybe my overclock is unstable? Well I reset to "optimal defaults" in UEFI and then adjusted the bare minimum from there (RAID, etc.), but it hasn't made a difference at all. I tried googling a bit and found that there might be a compatibility problem with Sandy Bridge and MPC-HC when using DXVA, but that was already disabled by default and that wouldn't explain why the stuttering is happening with everything else now. So I have no idea what's going on and would really like some input before I start screwing around with everything trying to troubleshoot on my own. Maybe somebody else has had a similar issue and knows a fix? Other info that might be useful: -I just built this machine and installed Windows last week, so there isn't much software beyond drivers on it. -I haven't noticed any extra processes. -I'm running beta nvidia drivers (290.36) and I have occasionally noticed the driver crash and recover during the past week, so I was already thinking about rolling back to the latest WHQL release. -All other drivers and software are latest release as well.