Nvidia GeForce GTX 460 - Crashes when using videogame application.

Whenever I start up my computer and play any video game, I can run everything perfectly at the usual FPS of 60. Within ten to thirty minutes, the game starts to slowly lag, and my my audio starts to sound all static-like in which my frame-rate drastically drops to 5. Shortly after this happens, I close the application but the video lag and sound static still persists, in which I restart my computer. After restarting, I do not encounter this problem again until I shutdown my computer for the night or take a large break (One-Two Hours).

(The bottom paragraph is exactly what I did in order.)
I removed, and reinstalled my graphical drivers, but that didn't solve the problem. I rolled back to a old, yet useable driver but it didn't solve my problem. I then re-formatted my computer hoping it would solve it, however it didn't. I found out my motherboard's chip set and Wired Networking, and RAID were out-dated, so I updated them. Still no solution.

Operating System is Windows 7 - Ultimate.
Ran the cmd -> sfc.exe /scannow and received no errors.
Didn't receive any blue-screens, nor "Driver has stopped working."

I apologize If I have a lack of information.

Cleaned it out a week ago, using compressed air. Before that, cleaned it a month ago when I first started having the problem. It's not a heat issue, It would stay at a constant 34-40. Here's the system logs.

Sorry for this question, but what is "av?"

Active Visual? And where can I find it?

Ran the cmd -> sfc.exe /scannow again, didn't detect anything, but I know this problem will happen again when I start my computer up again.