When I first saw the almost flat voltage lines of the stability test I thought my testing is flawed. I retested and the numbers were indeed correct. The ToughPower 550W offers the most stable lines of all our PSU reviews so far. Especially the 12V line where most components draw power from is exceptionally stable.
Having two SLI connectors emphasizes that this PSU is built with overclockers and enthusiasts in mind. All cables are good in length. The cables with the 5.25" connectors on them are very long which helps in big cases.
This powerhouse PSU has a small drawback though, it is not the quietest. But if you are planning to run two video cards, you are expecting some extra noise, anyway. Same goes for the price, if you need to have the best, you will have to pay for it. Another "price factor" you have to consider is that the overall efficiency is a bit low with just 71%.