I have the following problem for about 2 weeks and I still can't find any solution
My computer spec is
CPU : Q6600
VGA : GTX 650 Ti
MOBO : G41-p33 combo
RAM : 4 G dual channel
PSU : 550 Watt
OS : Win 7 (and also try win8 but problem didnt solved)
Before 2 weeks my old mobo broke down and I buy a new (the G41-p33). So the problem is that games or programs like movie maker does not use the gpu. Or some games use it for some seconds only.
So a game starts with 60fps (100% gpu load) and after 5 second goes to 20 fps or less (no gpu load or below 20%). Some other games like Crysis 3 does not even load sometimes (with the latest nvidia driver with older drivers it load but play in very low fps and also uses 100% of cpu and 20% of GPU).
I have try everything. Changing OS and reformating.. Downgrading Drivers (this worked but not at all and for everything). Updating drivers, every possible performance and stress test, mem test , cpu test.. I change PSU... And many thinks and everything during test seems fine but the problem still exists.
I also used OCCT to make a gpu test. With some settings on nvidia control panel it run for 5-6 second at 60 fps and then at 10-20 for the rest of the test (it does the same think with games it loads everything to CPU) , but with some other nvidia control panel setting it run all the test @60 fps.. With the second setting the games or other programs still dont play.
In gpu-z the "performance test" it has if I press it, I take 70-100 fps with gpu load @99% for unlimited time..
When I try adding a different VGA the ati 6570 my computer worked fine all games played well with normal fps and they load correctly..
Crysis 3 load and play perfect etc in both win7 and 8...
When I give my vga to a friend and he try it in his (older) computer also everything worked !! He play tomb rider 5 in more that 35fps in ultra high setting and the gpu load was ~80% probably he bottlenecked by other older parts but I think it was a good performance.