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Re: Recommendation for Fedora server?



Bob Goodwin wrote:
Les wrote:
These supplies are switching supplies, not linear.  You should check
some of the draws, I think you will be surprised about how little some
of them draw (admittedly there are various design strengths out there.)

In general, a linear supply is about 20-35% efficient, meaning that a
450 watt supply would draw about 90 watts all the time.  But these new
switchers are about double that or more, meaning that the supply will
draw somewhere between 20 and 50 watts.  Moreover that draw will
basically be independent of the size of the ultimate supply, simply
existing to control the switcher itself, and not the drive current. Technology exists in some forms of "buck control" that could boost the
on line efficiency further reducing the drain.  Power stuff is evolving
even faster than much of the other technology, but is less glamorous, so
doesn't get as much of the press.

Regards,
Les H

Here's some more interesting information on power supplies. Note that best efficiency is attained at/near maximum load. So a 500 watt supply looks good but may not be what you want when considering power consumption and disposing of waste heat.

http://services.google.com/blog_resources/PSU_white_paper.pdf

Bob Goodwin

Hi Bob, I am interested in what Google has done but need a lot more information. They say changing the PS to one making just plus 12 volts will save energy. I do not see that as a given. In fact it makes me think they are just passing on the voltage change to the mother-board makers. I think the idea being the MB makers can make just the other voltages their board needs. But converting 12 to 1.5 volts with economy of power is complex and will jack up the MB cost somewhat, and will make it hotter.



--

	Karl F. Larsen, AKA K5DI
	Linux User
	#450462   http://counter.li.org.


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