I reinstalled my Nvidia Driver but can't get stable FPS yet

[Mastery]

My Specs:

GTX 780 3GB ACX COOLER EVGA
I7 4790K ( Never overclocked )
16 GB RAM CORSAIR VENGEANCE
750 WATTS ThermaItake 80 PLUS
MB: H81M-A/BR
And
A Water Cooler from Corsair

I use Windows 8.1 Updated

 

[Coolboy951]

Use DDU driver uninstaller because it gets rid of everything, but when you do it normally theres left over things behind
follow instructions
http://www.guru3d.com/files-details/display-driver-uninstaller-download.html

If that does not help Defrag your System with Smart Defrag
http://www.iobit.com/iobitsmartdefrag.html

select your Hard driver and than click the arrow on the defrag button and click Defrag and Full optimize