If the system draws 65 watts and you pay 12 cents/kwh, then it will cost you right at $68.377 dollars a year to run it at full tilt. Math: 1,000 watts /65 watt

If the system draws 65 watts and you pay 12 cents/kwh, then it will cost you right at $68.377 dollars a year to run it at full tilt. Math: 1,000 watts /65 watts/hour = 15.384 hours per kwh. 365.25 days/year * 24 hours/day = 8766 hours/yr <=(accounting for leap days) 8766 hours/yr / 15.384 hours/kwh = 569.81 kwh/yr 569.81 kwh/yr * $0.12/kwh = $68.377/yr For quick math where accuracy isn't very important, at $0.12/kwh it will cost you ~$1.05/year per watt (65w = $68.38/yr), so every watt you save per year is a dollar in your pocket. Of course, there are ways to reduce the energy usage of a system, a computer rarely has to run at 100% 24/7/365 unless it is very underspecced for your use case, even things as simple as enabling C states and not utilizing all of the PC resources available will save you many dollars a year.