BleepingComputer.com: nVidia GTX 550Ti Choppy Game Play

Does anyone have any ideas on why games like Skyrim, Rage and Oblivion are choppy and eventually unresponsive? They start out fine then after about 20 minutes it gets choppy and often freezes up. I have an nVidia GTX 550Ti video card and added a rear case fan to try and help the problem. I also installed a new hard drive (Seagate 500GB 7200 rps. Here is the dxdiag:
System Manufacturer: Dell Inc.
System Model: Studio XPS 8000
BIOS: Default System BIOS
Processor: Intel® Core™ i7 CPU 860 @ 2.80GHz (8 CPUs), ~2.8GHz
Memory: 12288MB RAM
Available OS Memory: 12280MB RAM
Page File: 1740MB used, 22815MB available
Windows Dir: C:\Windows
DirectX Version: DirectX 11
DX Setup Parameters: Not found
User DPI Setting: Using System DPI
System DPI Setting: 96 DPI (100 percent)
DWM DPI Scaling: Disabled
DxDiag Version: 6.01.7601.17514 32bit Unicode

Any ideas would be much appreciated. The only components I haven't replaced are the motherboard and processor. (I checked the thermal paste and it was just fine too).

Have you tried updating the video card's driver?

Keep an eye on your temps with speedfan http://majorgeeks.com/SpeedFan_d337.html

Make sure to do a clean install of the latest video drivers and don't let windows install your video drivers in the future.

Due to the significant changes in Nvidia driver packages over the last year and the surrounding confusion in how these changes have effected installing and uninstalling Nvidia Drivers, a clear outline of what those changes are and how it effects users has become extremely important.

http://www.evga.com/forums/tm.aspx?m=1174372

good luck

Abseil