I have this strange issue with my PC. I recently upgraded my video card from an HD Radeon 4850 to a NVIDIA gtx 560. I downloaded the driver and restarted the computer and all of my games ran perfectly fine. However, when I restarted my computer again, all of my games ran with frequent stuttering. I've tried defragging and it didnt solve the issue. However, whenever I update the driver again, my games run fine again. Help would be greatly appreciated!
Computer specs:
CPU: AMD Phenom II X4 810
Motherboard: GA-MA790FXT-UD5P
RAM: 8 gb
Video Card: NVIDIA Geforce GTX 560

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