PC Power Consumption

Well if you run games like bf3 or c3 that make your cpu/gpu you know,work more th epsu consumes more power=more $$ payment.

You really need a watt meter, they are not expensive. You can work out somewhat if you can find accurate data (mostly from reviews), but to be sure you need to measure yourself. I swapped a 3870 for a 6450 in my media PC expecting a few watts and it barely made a difference, this most likely due to the cheap PSU and the way PSU efficiency works. It did of course nearly eliminate noise though. A cheap PSU can really waste a lot of energy, so can buying one massively of range to actual use, ie a 85% rated 1200W power supply might be only 50% efficient when running at say 200W.

Don't forget your monitors also, I run 3, 19" 4:3 CRT, 19" 16:10 LCD and a 24" 16:9 LCD. The CRT uses more power than the 2 LCDs together.

Cut the plastic of the psu wire, lick your finger and place it CAREFULLY on the naked wire. Remember not to wear plastic shoes, you have to touch the ground bare foot.

pcpartpicker.com has an estimated wattage option when you make a build on there

I can tell you that in a month, even the most inefficient powerhouse of a PC won't use that much money worth of electricity.

If you have a gaming rig with a 1000 watt power supply, and it's using the FULL 1000 watts constantly (which is almost never the case) then that PC runs at 1 kilowatt per hour. So in a month of running constantly, the PC would use around 720 kW. The national average rate is like 10 cents per kWh. So in a month, that PC would use $72 worth of electricity.

But this would never be the case, as the PC is not going to be drawing power 24 hours a day. When not in use/idle, the GPU, CPU, hard drives draw MUCH less power than when they are in use. When idle, that PC may only use a third or a quarter of the electricity that it uses at full draw. So that cost per month in reality is probably way lower than that, like maybe a third. If you only use the PC for say 4 or 5 hours a day and the rest of the day it's idling, you could go as low as maybe $30 a month, possibly less.

A standard gaming PC with maybe a 750w PSU being used 6 hours a day and sitting idle the remaining 18 hours would cost somewhere around $15-$20 a month at most.

80 plus means at 20 percent, 50, and 100 percent you will get at least 80 percent efficiency so only up to 20 percent goes to waste

Things to take into consideration:

CPU Power consumption in Watts

GPU Power consumption in Watts and Amps (check the 12v rails)

Having more hardware will mean more power consumption, but unless it's another CPU or GPU, the consumption rates shouldn't be too substantial.

The typical PSU used nowadays can vary greately from computer to computer, as well as brand and model, but if you want to be on the safe side, you can get yourself a 650w PSU or higher, if you don't know which one to get, consult it here or at a hardware forum and you'll get your response pretty quickly, but do not skimp on it or buy the first one you see, that's a very common mistake to make.

As for monthly costs, i cannot answer that, as i don't know the rates for the region you are nor any other electrodomestics you have plugged in your house, if you really want to know that, you should go to your electricity provider and ask for a rough cost per watt so you can calculate that off from there.