text: It probably costs about 10 cents per kilowatt-hour to run a PC 24/7, depending where you live.  Most electronic gear is labeled with the power requirements in watts.  Just multiply that by 24 to get the watts per day and divide by 1,000 to get kilowatts.  For example, a 100 watt load times one hour equals 100 watt-hours and multiplied by 24 hours equals 2,400 watt-hours per day.  Dividing 2,400 watt-hours by 1,000 equals 2.4 KW-hours (kilowatt-hours) per day.  This would cost 2.4 time 10 cents or about 24 cents.  Of course, the PC and the monitor each need to be calculated separately.  Also, if the PC is not in constant use it may go into "sleep mode" reducing the power drain.  I read that some people never shut off their PC's because re-starting them may subject the chips to frequent power surges reducing chip life.  In the winter, I consider that the power consumed by my PC helps heat the house.  What is the difference between a 1,000 watt electrical load such as the cooking range vs a 1,000 watt electric heater?  Only the location.  Good luck.