Short version: AC watts = the watts pulled from the wall, as reported by your KillaWatt. Insert this number into A1, then B1 will report your average monthly hydro cost for running the equipment. Somewhat lengthier version: Yeah  so a computer uses DC power, which is why it needs a PSU: to convert AC power from the wall into DC power for the machine. There is a certain amount of power that is lost in this conversion (usually articulated as the efficiency rating of the PSU), so your AC wattage will be higher than your DC wattage. Since it's the AC wattage (i.e., the power from the wall) that affects your hydro bill, make sure to use that instead of any softwareorotherwisederived measurement of DC power consumption. Hence the need for a KillaWatt or similar AC measurement apparatus. This little gizmo might give you a few different metrics  volts, amps, etc. The one you want is watts. Note that it's normal for your AC wattage to jump around a bit. It can vary by as much as +/ 10% when under a seemingly consistent 100% folding load. Up to you if you want to use an estimated average based on the KillaWatt readouts or if you want to enter the peak wattage (this is what I do).
