From the wall vs system power comsumption...

[Massa9]

I never understood what exactly "from the wall" means.  At one time i thought that a say 750W PSU Working at about 60% is not going to draw more than 450W from the wall.  Then I read that the System Power , CPU, GPU, RAM,...Hard drives, ect  is completely different number than what is being drawn from the wall, usually that number is higher. ... As you can see i am confused by the terminology. enough so that this might not make any sense.   And am not even going to ask about  Intel's TDP ratings.. 

 

[TheKDub]

Power supplies do not run at 100% efficiency, which means some of the energy consumed by them is converted into heat and such, and the rest remains as electricity which then goes to power your pc's components, that is why the power drawn from the wall will not be the same amount as that being put out to your pc's components.