Lag. (Counter-Strike: Global Offensive)

Hi all.
Actually I have a problem. Have hanging out of the COP in randomly time. Either hangs for 20 seconds, or the dead. Just slows down the picture on the desktop will not let me.
Before that there were failures in the black screen, played on TV by hdmi and just get a black screen and resolution information from the TV comes in, then everything comes back to normal.

Settings cs go low at all.

The actual iron:
Windows 7 x64
intel core 2 quad q8200
msi gts250 512mb
4gb ram
CPU overclocking up to 2.8(without overheating)
The video card in default. (new video driver)

Lags are observed only in cs go.
Far Cry 3, Outlast 2, Dirt 2, Dirt 3, Dead Space 3, coming with absolutely no lag. Well, that's all.