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

Ed Plese ed at edplese.com
Sun Feb 6 15:33:23 UTC 2005

On Wed, Feb 02, 2005 at 10:23:30AM -0500, 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.

I don't think this is possible, at least not with ATX and newer power supplies.
You may be able to get this working with old PCs that use AT power supplies.

The ATX spec adds not only a 3.3V wire, but also a wire to remotely sense the
voltage of the 3.3V wire at the motherboard.  The remote voltage sensing is
used to compensate for the voltage drop across the 3.3V wire from the power
supply to the motherboard due to the high current (amps) flowing through it.

The main problem you'll run into is that you can't split up the wire that's
used for remote voltage sensing for the 3.3V wire.  It's the equivalent to
simultaneously connecting a 9V battery and a 1.5V battery to a voltmeter and
trying to independently read their voltages.

My guess would be that if you do just splice the wires together, you'll end
up frying one of the motherboards because it will be fed too much voltage on
the 3.3V wire.

You can probably do this with old AT power supplies because all of their pins
are strictly outputs that can be spliced together.


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