power saving mode after a few minutes on gaming

Hello everybody,

i playing max payne 3 and a few minute after the screen into a mode power saving mode..

the computer stuck and the sound like a buzzy

the problem stay on a many games

in borderlands

gta iv

and more..

but not all!!

i have a gaming computer:

I5 760 2.80GHZ

Memory 4096MB RAM

motherboard: P55A-UD3

GPU: AMD ATI 6850 HD

WINDOWS 7 64BIT

i tried to format my computer and the problem didnt solved..

i changed the power settings in control panel

i replaced the lithium battery in my motherboard

but the problem didnt solved

i try to use a software for check the temperature and the memory of the video card and i see a problem

please download the log to see my problem

https://dl.dropbox.com/s/zd3vr0kh12h...20Log.txt?dl=1

go to down and see the memory of the card

from 10:15:59 the problem start

from 10:16:05 the computer do a restart