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#11
MTP as my understanding of the machinations of PSU's is that they adapt the power draw from the mains in direct correlation to what the machine is using = say the machine is requiring 200 watts of DC power at idle then the power from the mains will be accordingly similar and that may be 220 watts of AC power (very rough example) when at high machine usage say 350 watts DC power is being required then the draw from the mains may well be 420watts of AC power. The efficiency is built into the PSU circuitry to sense the amount of power being used and adjust the power being drawn.
Now that efficiency of any PSU is measured by the manufacturers as a percentage of the power converted from AC to DC. The figures quoted as 80% is then rated by colours meaning that a gold 80% rated device is better than a silver 80% PSU. See the efficiency levels in this link 80 Plus - Wikipedia, the free encyclopedia
So in reality the PSU will always draw more watts (AC) than what (no pun) is being produced as watts (DC) power. That is simply because there is always some power loss in every component in any electronic device.
To give you an idea say pass an electric current through a resistor the amount of power at the "outlet" end will be less than the input because the passage of the electrons causes heat to be produced by the mechanism of friction for want of a better analogy and therefore taking the laws of the conservation of energy the total energy in will not equal the energy put out.
The same goes for all electronic components and a good example of this is of course the CPU!
So wherever that information came from is wrong especially of the technology behind how those electronic components and devices are now made. Again and lastly for an example of the power being dissipated - a power transistor of this day and age compared to the old power output vacuum tubes of a few decades ago is light years apart.