One question have you been overclocking the CPU?
First thing I'd do before anything is download/reinstall the chipset drivers for your motherboard, and restore any BIOS defaults if you played around with any overclocking like BubbleMax mentioned. Also make sure Windows is set to balanced or max performance for its power setting. Also do a Clean Boot, to make sure no background services are running that are affecting your performance either. The last resort software troubleshooting steps would be to complete uninstall and reinstall the game, or reinstall Windows entirely. You could also try a BIOS update if that doesn't do it.
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