atmartens wrote:To find the "greenest" CPU, first determine what you need to do. Then, find the processors capable of doing that task. Take the one that is capable of performing that task and that consumes the least power. It's wasteful to buy more CPU than you need, and it's wasteful to buy a CPU that can't do what you need.
Agree definitely don't want to underbuy - which is what makes a lot of the low power, so-called green machines of dubious greenness. From a green perspective, better to overbuy (to a modest extent) than to get just what does the job now. (Since the software almost always gets more demanding as time goes on - Wirth's Law.)
So the greenest CPU would be (in approximate priority order):
0) Except for special circumstances, there are probably other areas where a home user can save a lot more than getting really hung up on CPU power efficiency. (Special circumstances would be things like: going to get several machines, running off grid.) (Other areas - things like heating, cooling, lighting, transportation)
1) CPU that don't spend an inordinate amount of time and energy shopping for, compared to the energy used by the CPU
[For instance, if one spends extra time shopping for the low-energy using CPU, and if average energy use of a person in US 10kW, then for each hour one spent shopping, that CPU has to use 10kW-hours less during it's lifetime in order to make up for the energy expended to support the person while shopping.]
http://en.wikipedia.org/wiki/List_of_co ... per_capita
(of course if one can put together a resource so many people use more efficient device, that would help offset the cost of doing the research.)
2) the one that will do the job at hand, plus handle the job for a reasonable time in the future, (longer is better)
3) That can get second-hand
4) That has low idle power (unless have special type of job)
5) Support chips/motherboard low power
6) Balances cost of chip versus cost of energy (return on investment for higher efficiency)
7) High performance per watt when loaded