Dude, first of all you are not using a GTX 550 TI! Second of all, drivers BEHAVE differently for EACH GPU. Third, I know what STUTTERING IS! I got 120mbps internet connection, which has nothing to do with having stuttering.
Why would the stuttering stop, also allowing me to use AA with good FPS after installing an older driver? Obvious stuttering and FPS behaving weirdly going up and down just because of the driver.
You're talking about internet lag, which got nothing to do with stuttering
Remains for OP to just use the driver I suggested and see if he still has the issue.