The calculator is a good talking point but I wouldn't rely on it completely. In some cases it's going to go way overboard and in others it will fall short. I put in my old c2d system with tri sli and it's recommendation using "recommended" settings is a 604W PSU. I saw that system peak at 700W at the wall. In other cases you guys are posting smaller systems with bigger estimates than I've seen people use 24/7. Since we don't know how they got all of those numbers it seems hit or miss whether it will be accurate.