Nice survey of higher end power supplies ...

Donald Becker becker at scyld.com
Wed Jun 11 16:40:31 EDT 2003


On Wed, 11 Jun 2003, Josip Loncaric wrote:
> Mark Hahn wrote:
> > 
> > PF .74 on that machine, by the way.  I was kind of surprised,
> > since it was a compaq deskpro.  pretty old, though, that's probably why.
> 
> Power factor is about 0.65 on my own machine.  I was kind of surprised 
> too.

I'm shocked at that low PF.  I had believed that most modern power
supplies had some PF correction.

> According to Kill-a-watt, my 2.8 GHz P4 w/Asus motherboard, lots 
> of other goodies, and a 2002-vintage Antec PS dissipates 130-180 Watts 
> in operation depending on activity.  Another disappointment was its 
> "sleep" mode which dissipates 100 Watts (not much better than the 130 W 
> idle state).  When "off" it still uses 5 Watts...

This doesn't surprise me at all.  Sleep mode on a desktop is no better
than executing a halt instruction.  Unlike a laptop, where all devices
are known and controlled, a desktop machine still has to leave most of
the system active to support unknown PCI or ISA devices.

This has the potential to change.  When most devices implement PCI power
management, the OS should be able to verify that there are unsupported
devices and tell the ACPI firmware to really turn things off.  But you
won't find this fully implemented for currrent motherboards.

-- 
Donald Becker				becker at scyld.com
Scyld Computing Corporation		http://www.scyld.com
914 Bay Ridge Road, Suite 220		Scyld Beowulf cluster system
Annapolis MD 21403			410-990-9993

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