On Saturday 09 February 2008 09:39:13 am Randall R Schulz wrote:
On Saturday 09 February 2008 11:22, Philippe Landau wrote:
Randall R Schulz wrote:
On Saturday 09 February 2008 10:08, Philippe Landau wrote:
But many power supplies are only efficient when they don't operate close to full load.
This seemed counterintuitive to me, so I decided to do a little looking around. According to the graph on page 14 of "Power Supplies: A Hidden Opportunity for Energy Savings" http://standby.lbl.gov/CEC_Workshop/Docs/Ecos_FinalReport.pdf this is not the case.
It very much depends on the power supply in question.
Of course.
But to go back to the original question (mine), the issue is whether highly over-rated supply is wasteful of power. It appears they are.
Randall Schulz
I disagree: I looked at a bunch of efficiency plots from 80plus.org. They generally peak at 50% of the rated load, at around 84-85%. their low load (20%) efficiency is around 82%, the high load (100%) efficiency is around 80%. so, for a 400 watt load, typical i would say for today's computers, an 800 watt power supply would draw around 470 watts, as it would operate at 85% efficiency. for the same 400 watt load a 400 watt power supply would draw 500 watts, efficiency at 80% for the same load, a 550 w power supply would draw around 488 watts, efficiencyaround 82% for the typical efficiency curve shown on this site, the same 400 watt load, supplied by a 2000 watt power supply , would draw 488 watts, as at 20% load the efficiency is at 82%. so, it is better to get a power supply at least twice as big as the load. Even when the rating is way greater, say 4 times the requirement, the efficiency is better than using a power supply at over 75% of it's capacity. the SUV syndrome fails when applied to power supplies:) d. -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org