I thought I'd share this because I've seen others with this problem, and in searching I finally found out what causes it. Bear with me if any of you already know this, because really there isn't much in the way of warnings about it. We all know that many whom have bought GPUs with built-in HD Audio via HDMI have had problems of one sort or another right? The scope and variety of them can vary. Many of us have also read that it's best to disable onboard sound in the BIOS when you CAN get HDMI audio to work. Did you know however that if you CAN'T get HDMI Audio to work, you run the risk of severe lockups in game, accompanied by loud audio stutter, if you leave the GPU's HD Audio device enabled in Device Manager? Many probably assume it's fine to leave it as is because Windows will only let you enable one sound device as the default. Well I'm here to tell you that those whom went into Device Manager and disabled the sound device not set as the default have reported no more in game freezes. The problem often doesn't show until well into a gaming session, so it can have the appearance of being mere overheating, memory leaks, or any one of many other possibilities. I had OCed my i7 950 to 4GHz, getting excellent results in Prime95 on just 1.3v, so I assumed I was not giving the CPU enough voltage when I got these lockups after a long session, since many use 1.35 @ 4GHz with this CPU. The lockups were merely due to two sound devices being enabled in Device Manager though. The reason I never get the lockups running Prime95 is obviously because there's no audio running at the time.