Actually looking at the other entries on the chart all the power values seem to be on the high side. I know some of those were applicable when using scrypt settings and overclocking, but for instance the 280x cards are showing 250 watts each. I have some 4x 280x rigs as well and they are only drawing about 150 watts each, also undervolted, and mildly overclocked.
The rig I am using for reference (4X 280x) draws 660 watts total from the wall, I first check the idle usage, which draws about 60 watts, then check after it has been mining for about 5 minutes, which is the 660 watt figure. Again subtracting the 60 system watts and dividing the remaining 600 watts by 4 gives me an average of 150 watts per card. These are giving me ~315 kHash each with a mild 1100 core and 1500 memory overclock. Since they are undervolted they are not stable much higher, but I only get maybe 10-20 more khash each for quite a large increase in power draw, so not worth it in my opinion.
Edit: Actually on further investigation, if I ran a 280x giving only 315 kHash at a 250 watt power draw (let’s assume this includes the pro-rated share of the system draw as well; i.e. 230 watt GPU 20 watts system on a multi-GPU rig), this would work out to just breaking even if you pay $0.08 per kw/hour. You would not be in profit unless you were paying $0.07 or less per kw/hour, which unfortunately in my case is closer to $0.10.