FW: [Malvern] PC PSUs

[Guy Inchbald]

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