Does anyone here know if a "500 watt" atx power supply realy pulls 500 watts @ 110 volts??

See I'm on this power kick since my bills like $350 a month and started looking into solar and make/saving power, well in my learning I found out how to find how many watt hours things use and how much they cost a month and if all 13 of my pc's here are costing $28 a month each to use looks like foldings only going to happen during the day

so far I've added a few solar pv cells and deep cycle batteries for 12 lighting in my shop , a exercise bike rigged with a 60 amp 12 volt altanator for the ol'lady and 100 gallon batch water heater,lol I sure hope these power supply dont realy pull that much I was doing so good