[Offtopic] sustainable IT

stephen at melbpc.org.au stephen at melbpc.org.au
Sun Feb 25 03:55:27 EST 2007

At 01:37 AM 25/02/2007, Roland writes:

> Golly Stephen, also seems to be getting a lot thinner. I wish more
> of our schools were sustainable and don't understand why we are
> not taking more steps in that direction.
>> <http://envisense.org/glacsweb/photos/briks-panos/index.html>

Yes :-) Eg, perhaps schools might like to support Google's proposal:

** High-efficiency power supplies for home computers and servers **
    By: Urs Hoelzle and Bill Weihl  for Google Inc., September 2006:


Most likely, the computer you’re using wastes 30-40% of the electrical 
power it
consumes because it is using an inefficient power supply. It’s difficult 
to believe that
something as basic as a power supply could be responsible for that amount 
of waste,
but it’s true. The problem with power supplies is that they generate 
heat, which saps
away energy meant to power the computer. That happens when the power 
converts AC current into the DC current needed by computers.

At Google, we run many computers in our data centers to serve your 
queries, so
energy conservation and efficiency are important to us. For several years 
been developing more efficient power supplies to eliminate waste from 
supplies. Instead of the typical efficiencies of 60-70%, our servers’ 
power supplies
now run at 90% efficiency or better, cutting down the energy losses by a 
factor of

We believe this energy-saving power supply technology can be applied to 
computers, too. So we’ve been working with Intel and other partners to 
propose a
new power supply standard. The opportunity for savings is immense ­ we 
that if deployed in 100 million PCs running for an average of eight hours 
per day, this
new standard would save 40 billion kilowatt-hours over three years, or 
more than $5
billion at California’s energy rates.

The technical changes we propose are very small and low-risk. For 
reasons dating back to the original IBM PC in 1981, standard PC power 
provide multiple output voltages, most of which are no longer used 
directly in today’s
PCs. Back in 1981 the chips actually did need all these voltages. But 
those times
are long gone.

Why then do power supplies continue to be built to produce multiple 
voltages? The
answer is simple: because the standard never changed, and because the 
voltage needs of many chips in a computer change every year as they 
become more
energy efficient themselves. But the changing voltage needs of chips are 
now met
by voltage regulator modules (VRMs) that computer manufacturers put on 
motherboards. These VRMs take one of these voltages (say, 5V) and 
them down to the actual voltage needed (say, 1.7V) making multiple 
voltage output
capability of power supplies unnecessary.

Providing multiple output voltages complicates the design of power 
supplies, and it
makes it harder to build efficient power supplies. In essence, 
manufacturers have to
build four different power supplies: one each for +12V, -12V, 5V, and 
3.3V outputs,
four power supplies in one.

Because each motherboard may draw different amounts of power on each 
manufacturers overprovision the supply for each individual voltage in 
order to
support multiple options. Since power supplies are most efficient near 
their maximum
rated loads, this overprovisioning leads to lower efficiency. The VRMs 
regulator modules) used internally are also a significant source of loss. 
current efficiencies (including power supply and VRM losses) are in the 
range today, i.e., power supplies use 65-80% more power than necessary.

Google servers, and the new PC standard we propose, use a simple 12V power
supply. The power supply generates a single voltage, and all other 
voltages required
by motherboard components will be generated on the motherboard itself via 

The net result of these changes is a dramatic improvement in efficiency 
the power supply and the regulators) to about 85%, at virtually no cost. 
In other
words, you won’t have to pay more for a higher-efficiency PC, because the 
supply is actually getting simpler, not more complicated. By spending 
another $20 or
so extra, it is possible to use higher-quality components and achieve 
efficiencies well
over 90%.

You won’t be able to buy such computers for a while, and Google isn’t 
planning on
selling you any. But we’re working with industry partners such as Intel 
to make this
technology an open standard that everyone can use, and that all vendors 
will adopt. It’s the right solution technically, and the right thing to 
do for the

If you'd like us to keep you posted on our progress, please send us a 
note at
efficient-psu at google.com.

Cheers, Roland
Stephen Loosley
Victoria, Australia

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