I read this: "A typical 14 inch monitor would consume about 80 watts."
and I was surprized to find out that other forums had no clue either...
although I read a reply suggesting that you turn off everything in your house exept your computer, then check the bill, but I think I would do it the otherway around...(ie: computer on, everything else off...)
good luck finding that info... you could look for a program that reads powersuply input... I couldn't find one
why does it matter how much the CPU uses? if you wanna work out how much the pc uses it will be what the is stated on the psu ( or Power Supply Unit). the monitor drains its own power unless connected to the psu like on some computers. a PC will most likely use less than air-con but more than a phone charger
p.s. if the sound is not from an internal speaker it will not effect the energy used by the computer. lol i was gonna go into a spiel about physics and had a hell long post typed up but deleted it to spare you guys