Not sure what you mean. I'm still talking about running 4x5850s. I have 2x5850s that pull 400 watts from the wall. 2 more would probably pull around 700 watts. A good 850w PSU will handle that no problem. And you can get 4 cards on a cheap mobo that has two x16 slots plus two more x1 slots. But you will need extenders for the x1 slots to work. I have a Biostar A870U3 ($65 Newegg) that will run 4 cards this way. It will still take a long time to pay off, but you will bring in just as much per month as you originally calculated (assuming that calculation was realistic).