yes it does matter lots to alot of people with older systems, crap power supplies, and thier system is alredy near its watt limit not to mention that you can oc it alot with just a little juice.. now if you have a 850 watt PSU like me its not an issue, also my room is hot as balls, i have three computers in here, 2 are OC, i have a 1200 wtt sound system and alot of other electronics, theres thousands of wats burning in my room and yes the electricity doesnt cost alot but the AC that i have to run to keep my room cool sure does.. less heat is nicer at least in the south, maybe in Norway it will be a benefit, free heating?