If you want to objectively, accurately and scientifically determine what PSU power is required for your Vid card and PC in both watts and 12v rail amps., the forum Utility link below will show you how easy it is to calculate this information and objectively determine which PSUs are quality built, reliable PSUs that can meet your needs. Be advised that the available 12v rail amps. is just as important as the total PSU wattage. You need both to be correct.
Take a look at the "Best PCs for X $" post that this website does every month.
They build quality systems completely under a series of $ ranges.
You can just count in the exchange rates and see if you can indeed construct the system in your area for the same cost and you won't have to worry about picking parts with poor reviews or poor performance.
I don't have the link at this moment but if I find it I will edit my post to include it.
If you can afford a single GTX580, it is better to go that route than 2 GTX560Ti's. This is for the future upgrade reason. If you run 2 GTX560Ti's, you have to restart with another series, as there is no room to go anywhere. These 2 cards together will outperform a single GTX580, but you wont need that power yet. Later on though, adding another GTX580 will greatly improve your performance.
If you are going to OC your cpu, you need an aftermarket cooler. I recommend the Noctua D14, Hyper 212+ (EVO), or Corsair H80/H100.
A good PSU for this system would be either an HX850/HX1050*, a PC Power & Cooling 910W, or anything around the 1000W range inside an 80+ _____ Certified. Companies to use are Ante, Corsair, Seasonic, PC Power & Cooling, OCZ, and XFX. There is a sticky for recommended PSU's listed here on TOM's, as well as some stickies that users have started to help calculate what you need for your system.