Working backwards; at $2 per month and lets say the cost in your area is ten cents per KWH rather than the 14 cents per KWH in the DC area. $2 buys you 20 KWH of electricity. Given that there are (30 X 24) 720 hours in a month, your computer burns 20/720 = .0277778 KW or 28 watts of electricity.
A very efficient computer indeed. Do you have a monitor with that?
If you put your computer, monitor, printer, etc. on a APC it runs just like running ONE VCR. -- Saving the world keeps me busy. However, I find Earth very primitive from my home planet of Krypton. -Supergirl