FW: FW: [Malvern] PC PSUs

[Ian Pascoe]

Guy and Steve - thanks

So what you are all saying is that what is on the box is not necessarily
what is underneath the hood.

That kind of makes me feel better - all of this comes about as I have just
got myself a box to play with as a servre at home for my vast PC network of
1!  Generally speaking you would leave a server on to it's own devices and
only ever reset when it needed to because of upgrades etc etc.  My worry was
that it has a rated PSU of 400w and that over a day / week etc etc is a lot
of power for not a lot of work.  Yes I know I can turn it on and off as I
need it, but some of the things I want to play with, and currently know
nothing about! will require it to be on 24 / 7.

OK, last question on the subject, honest!

When a system is either forced into, or drops into hibernation / standby,
does this actually put that component into an idle state or actually turns
it off waiting for the trigger to re-start?  Or is it again a case of
symantics?

Ian

-----Original Message-----
From: malvern-bounces at mailman.lug.org.uk
[mailto:malvern-bounces at mailman.lug.org.uk]On Behalf Of Guy Inchbald
Sent: 08 February 2007 15:24
To: Malvern at mailman.lug.org.uk
Subject: Re: FW: [Malvern] PC PSUs



A few thoughts on PSU's:

One reason that PSU's are often rated well over the PC's actual power
consumption, is that the max. output of the various voltage rails seldom
exactly matches the individual PC. So some of the outputs will be
under-used.

Another is that a PC seldom draws maximum wellie. Probably only when
simultaneously playing a fast, graphics-intensive game moment with lots
of physics going on, while also loading the next scene from hard disc,
etc. etc. Most the time, the CPU and graphics card will be just ticking
over.

A third is that bad bunnies often abuse the output specs: say a PSU can
deliver 200W to the 12V line OR to the 5V line, but only 100W on each
simultaneously. It's easy to brag that 200W capability on each line
equals 400W. About a year ago I read a comparative review of 10 PSUs,
where they ran each PSU at 100% rated output for 5 mins. Only one
maintained its rated output for the full 5 mins. Two burst into flames.
The others came somewhere in between.

Somebody said that switched-mode PSU's tend to be erratic under less
than max load. ISTR that 10-20% is usually enough to stabilise them.

The difference between PC's and high-end audio is that PC's have all the
bare bits inside a single box. Giving every pluggable toy its own
electrically safe enclosure would be a cooling and packaging nightmare,
never mind all that mains cabling coiling around inside. The PC would
end up four times the size and four times the price - and probably have
to run slower. So why don't audio systems do things the PC way? 1. No
need for manic cooling. 2. Much slower data rates, so tight electrical
packaging is less important. 3. Nobody has ever been in a dominant
enough position in the industry and then declared an open standard for
hardware plug-ins.

--
Cheers,
Guy

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