I've had this problem for a long time now.
I have even spent £400+ on trying to fix it, replaced my motherboard, CPU, PSU & Graphics card.
All Drivers i've updated and uninstalled and installed old ones and uninstalled and installed beta drivers and so on.
It happens if i'm browsing internet through to playing Crysis games.
Some days it doesn't even happen at all.
I am very frustrated by this and am losing the will to keep trying.
Here is the Speccy log;
I'm aware my memory isn't the greatest, thats next on my "to upgrade" list. I only hope its the memory that is the problem, otherwise i havn't got a clue.