The Macbook Pro Model MC374, MC375 from 2010 consumes only 6.6W when idle (without display) when powered with 100V to the power supply.
How can I build a modular, high-spec computer which will have similar power consumption when idle - i.e. when the system is normally running, but the user (nor any daemon on the system itself) is doing anything, just waiting for user input?
I do not care very much about the power consumption when the system is used, but I want the power consumption when CPU utilization is below 1% to be as low as possible.
I don't want the Mac, because I want the machine to be as modular as possible, preferably not a laptop, which are never too modular, but maybe some mini-ITX or even full size ATX board.
I would like to be able to have at least 4 GB RAM in the machine, preferably 8 GB or more, and for it to be a powerful computer when used, comparable in processing power to a AMD Athlon64 4000+.
Do component (motherboards, CPU, memory), from which I can build such a machine exist?
Are there any tricks like undervolting, underclocking that I can use to reduce the power consumption when idle without losing too much processing power when non-idle (losing 50% is OK)?