I have the 2gb 560Ti and it runs fine, however I will run into overheating issue and have to manually turn up the fan speed to about 70 percent with some extra software.  I'm not sure if you will have same issue with the 550ti.

Whats ur budget, you might have different options


Also have you updated all ur drivers and maybe even update the firmware on ur card.

Or even aftermarket cooling for your 560ti