Mailinglist Archive: opensuse (3031 mails)

[Philippe Landau <lists@xxxxxxxxxxxxx>]

James Knott wrote:
> Tom Patton wrote:
> > On Thu, 2008-02-07 at 10:13 +0100, Per Jessen wrote:
> > > Randall R Schulz wrote:
> > > > Offhand, I don't know how the efficiency of today's power supplies
> > > > varies with the percentage of their rated output they're producing. In
> > > > other words, does a higher-capacity PSU consume more mains power for a
> > > > given level of consumption on its output side? If so, you wouldn't
> > > > want to have such a large PSU, since that would be wasteful.
> > > I haven't looked at switchmode technology for quite some time, but I
> > > would expect a fairly fixed efficiency in the 80-90% range, quite
> > > probably more.  There will be a minimum consumption required in order
> > > to achieve optimal operation, but otherwise I think the output power
> > > will be e.g. 80% of the input power, and the rest is turned into heat. 
> > or to say it another way...(at 80% efficiency) a 150 watt supply or a
> > 500 watt supply should either one pull the same current from the mains,
> > if they alternately supply the same 80 watt load (ie MB)...approximately
> > 100 watts from the mains in each example.  It would NOT be wasteful to
> > the environment...(but maybe to your wallet).
> You're forgetting there may be some additional power consumed by the
> power supply itself.  This might be a bit more for a larger supply. 
> Even with no load, all power supplies draw some power.
But many power supplies are only efficient when
they don't operate close to full load.

kind regards     Philippe

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