Gospada! Slow toy on my PC/laptop.. Help!

Hello, the problem is not new, a lot of topics on various forums created, but almost everywhere they are not disclosed, but if some way is, to me, unfortunately, not helped, mostly face a similar problem on laptops due to overheating of the graphics card.
Before such was not, the essence of the problem : during the game (any of the less modern BF3 for example, and the like, as of old, but World of Warcraft as well behaved) after 10-15 minutes begins to sink to 5-10 fps for 5-8 seconds and after a while again repeats.
Har-Ki the stationary computer:
Windows 7 Max
Arctic Freezer CPU AMD Phenom(tm) II X6 1100T Processor, 3300 MHz, cores: 6, logical processors: 6
Installed memory (RAM) 8,00 GB
NVIDIA GeForce GTX 560 Ti Twin Frozer 2GB (driver Version 320.49, the last)
Motherboard Asrock n68c-gs fx
The power supply 600 w
Then it all began is not known. The body in the hole and an additional 2 cooler, dust very little. It has been speculated that the problem is the video card tested on another computer on the same games, pretty fun for a week, found no single freeze, fps is high and stable at high settings. When sags FPS on vidyahe, sags GP, but the temperature is not changing,the normal game in WoW is around 50 degrees and keeps the workload of GP 40%(sags to 20%) uses somewhere 500 MB, BF3 on ultra the workload of GP 100%(sags to about 40-50%), temperature 70-80 degrees and is about 1600 MB.
Processor checked Everest, the temperature at full load is around 50 degrees, the test was 10 minutes, actually no longer required, the increase nowhere to be seen, here's the screenshots.
http://s1.ipicture.ru/uploads/20130822/D7JSS1b9.jpg
http://s1.ipicture.ru/uploads/20130822/1NWVViOD.jpg
http://s1.ipicture.ru/uploads/20130822/ZSR2mwWR.jpg
http://s1.ipicture.ru/uploads/20130822/d85mscds.jpg
Please tell me what I can do.