New and Better Graphics Card. Low FPS. Driver Problem?

[TacticalScheme]

So I just upgraded my PC today from a gtx 550ti to a Gtx 660ti. I also upgraded the processor to a i7-2600k. Everything seemed to be fine until I went in game. I got low FPS in every game I played. I thought it might be the drivers so I tried to uninstall all of them and reinstall them. No luck. I dont know if I did that incorrectly or not but I believe I did it right as I tried about 3 times. After that I wondered if the integrated graphics would be taking over the Gtx 660ti. I never did try to fix it because after research I learned that it automatically disables the integrated graphics if a dedicated GPU was found. So now im stuck and could really use some help. Possibly I might of screwed up the drivers some how but I dont know how to fix them. If anyone could tell me any ideas they have please help me out. And dont be afraid to post more than one solution either. Thanks guys ive been stressing over this all day .
OH sorry. PC specs here.

CPU- i7-2600k
GPU- Nvidia Gefore GTX 660ti.
RAM- 8G 1333 DDR3
MotherBoard- Asrock H61M-HVS

 

[AMD Radeon]

what psu? low power psu might cause low performance GPU

 

[TacticalScheme]

600watt. Should be enough to run a 660ti and i7-2600k.