All true, and the other issue is the power consumption.
If, for example, you have a wife that nags about you leaving a light on when you leave a room, this is a good way to get back at her...
Seriously, 350 Watts is a lot. An alternative is a temperature controlled power supply (and I will build one) that keeps the CPU at the same temperature all the time, regardless of what it is doing (idle/full load).
I'll put together an article on it (don't hold your breath though, it'll take time).
You can also purchase such a PSU, but expect a $200+ expense.