Bf3 gameplay choppy

hi guys i found out my corsair vengeance ram had some errors after i ran memtest on them so i bought the same pair earlier today. I checked everything and it came up with no errors. But when I went to go play bf3 the game play was feeling jumpy like I was lagging, i could mostly feel it when id aim down the sight. With my other ram everything was playing smooth but now its like this. any help? javascript: void(0);

specs:

i5 3570k
asrock z77 extreme4
corsair vengeance 8gb
evga gtx 660 ti
630w psu