I think you mean Asus, not BFG for the motherboard...as maximus or striker are the codename they used for their enthusiast boards. From what I recall, they will support both Crossfire and SLI, so you should be fine there.
As for your PSU, if you can...open the side panel (I'd suggest you to do this with your PC off) and have a look at the label on the PSU for its brand name to make sure it is not some nasty, generic brand.
The reason for this it is agreed that the PSU is essentially the most important piece of hardware in the PC, as if the quality of the PSU is poor, it could go BANG when stressed, and taking the rest of the PC with it...and considering you got a i7 CPU, high-end motherboard and soon pair of GTX560Ti, I think you definitely would not want that to happen...so you should really try to identify the brand and the model of the PSU you using and let us know, and we will confirm for you to make sure it is not of a poor generic brand.