Would this fit? Also.. When I overclock my stuff ( CPU, GPU, RAM ) Would I require a higher wattage for my PSU?
More aboutpower supply
it should be enough for your need. that psu should be able to handle your system and 2 GTX560 Ti in SLI.
That power supply could drive two of those cards. And yes, when you overclock your stuff wattage need increases, but the power supply you have chosen is a very good power supply, and as I said, you could even run two cards on it without problems.
I have 3 of those cards (they are really sweet...reasonably fast and very, very cool). One of them is running off a 450w power supply with no problem. Even overclocked the whole system pulls less than 300w when playing games.
You should be perfect with the power supply you have.