10% over thousands or millions of computers is a lot.
No it fucking isn't. This is the same bullshit bad math greenies are always spouting. "If everyone does a little, it adds up to a lot" Big savings require BIG changes on the part of each individual. If you save 4W displaying black screens on you LCD, even if you run it 24/7 for a year, you're only saving the equivalent of ONE FREAKING GALLON of gasoline.
Carnot efficiency is the maximum possible energy efficiency that any possible heat engine can achieve, when perfectly designed, engineered and operated without real-world constraints like friction and dirt.
If you are achieving 35% energy efficiency, and Carnot is 73%, to double your efficiency you need to create the PERFECT engine and operate it in a cleanroom. THIS KIND OF IMPROVEMENT WILL NEVER HAPPEN. If you are lucky you might be able to squeeze another 10% out with your ridiculous waste heat capture scheme.
And nice job completely changing the subject with your 1mpg non sequitur. I can tell you right now it's not going to affect oil usage by more than a few percent, so suck my dick.
Just because your impatient ass wants to blast past everyone else doesn't mean we have to move over and make way for you.