power consumption - was RE: [K12OSN] Get rid of my PCs

Gavin Chester sales at ecosolutions.com.au
Wed Feb 2 18:30:45 UTC 2005

On Thu, 2005-02-03 at 02:06, Robert Lefebvre wrote:
> These are low voltages, correct? I'm not expert but I understand that
> the lower the voltage the bigger the wire needs to be to carry it
> without a voltage drop. If we figure 5 computers on one power supply
> the furthest ones would be about 5 feet away from the power supply. Do
> we have anyone who knows if this would be a factor?

FYI: You have three voltages on ATX power supplies: 3.3, 5 & 12V DC and
different wires carry different currents for each. You are right in
stating that lower voltages require bigger wires/conductors to travel
along to avoid power loss with distance.  

However, if you are talking only up to five feet (<2m) then you would
get away with extending the conductors with wiring as large as that
already coming from the power supply (as a guide), which is something
like 14/0.20mm (that's wire talk and means 14 strands each of 0.2mm
thickness - equivalent to light weight speaker wire in your car).

If you have the knowledge, or the assistance of someone with that
knowledge, then what you are proposing is workable and a good
initiative.  However, it will look like a mess of spaghetti behind your
PCs and the best option would be to have a junction box in which all the
wires branch or terminate and then use a single cable with the requisite
number of conductors (say 8, or whatever) in one sheath to go to each
PC.  Also, there is potential to get one of the many conductors mixed up
and fry your motherboard if you make a mistake.  That said, I believe
you have hit on it is the best low-cost option for saving heat, noise
and power.

Regards, Gavin      
> On Wed, 02 Feb 2005 09:38:01 -0800 (PST), Gavin Chester
> <sales at ecosolutions.com.au> wrote:
> > On Wed, 2005-02-02 at 23:23, Robert Lefebvre wrote:
> > > Would it be possible to simply disconnect 3/4 of the power supplies
> > > and run them off of the remaining powersupplies?
> > > A few feet of  wires would do the trick.
> > 
> > Good idea - that would be the cheapest option if the computers are all
> > in one lab and wiring runs didn't exceed a few metres each to avoid
> > power loss over thin wires.
> > 
> > However, that would get into the realm of having sound knowledge of your
> > electrical wiring requirements to be able to patch together "branches"
> > of ATX wiring coming from each individual power supply.  You would also
> > have to make sure that each voltage & conductor combo didn't exceed the
> > rating of the power supply.  That is, if you look at the specs of your
> > power supply you'll see, for example, that one conductor is rated at
> > 0.5A @ +5V, another conductor at 3.5A @ +5V, and so on.  In other words,
> > I'm repeating the warning "sound knowledge of your electrical wiring
> > requirements" are mandatory for any option like this.
> > 
> > In an ideal world I'd like to see a complete K12LTSP lab running on
> > solar power - combine that with recycled cast-off thin clients and then
> > you would have an environmental/political statement worth making :^)
> > 
> > BTW: it helps the flow of reading in a threaded mail list if you retain
> > pertinent parts of the previous postings so that new-comers to the
> > thread can see what you are replying to :^)
> > 
> > --
> >         Regards,
> > 
> >         Gavin Chester
> > 
> > 
> -- 
> MissionaryNet.org - bringing the 21st Century technology to The Great Commission

More information about the K12OSN mailing list