> 1) Because electricity costs money

not to an extent that really matters to a home user. let's say you actually let your cpu draw 250W 24/7. average US consumer electricity rate is ~$0.13/kWh. that would add ~$23 to your monthly electricity bill. certainly a lot for a single component, but not likely to matter to the sort of person who would buy a high end cpu in the first place. if you could get the same performance using 100W, you would only save about $14 each month. and of course most people don't max out their cpu 24/7, so the actual savings would be even less.