Tripple Channel Ram is meant for the 1366 Socket, you are looking at the 1156. If you're certain on the 1156, I would go to 2*2GB ram, otherwise you will be looking at 2*2 plus 1*2, which will likely run slower than just going with the 4GB.
A better (IMO) idea would be to go to the 1366 Socket, with a 950. Google "1156 PCI lanes" to get an idea of what I mean, especially with a USB3.0 board and 2 480's.
Regarding power, are you looking at overclocked 480's, either yourself or factory?