Can my PSU handle GTX 550 Ti

That PSU does not look good, but even if it is really only good for 450W, it will run a GTX550Ti.
Avoid CM. Although they have a very few good units, they have many others that have liar labels and/or claim protection circuits that are missing. That's dishonest, and a dishonest company does not deserve anyone's business, for any of its products.