Power suppy that runs several motherboards

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We are trying to find a motherboard that will run multiple
motherboards, we essentially want to stack garden variety motherboards
in a tight rack, and run as many as we can off of one power supply.

The motherboards have a IDE HDD, all-in-one motherboard and a stick of
memory in them.  Right now, we have 1 Power supply running off of each
one... not very power efficient.

Anyone ever see anything like this?

We're making a cluster, but want to fit more machines in a tighter
space... Cases take up a lot of space, as well... hoping to save on

Re: Power suppy that runs several motherboards

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I can see some counter-arguments to your premise. Having one PSU
per motherboard limits the fault group to the one board. Using
central power for a whole bunch of boards means a PSU failure
ends up disabling the lot. A PSU failure that delivers high
voltage to any one of its DC outputs, would damage the whole
lot of boards as well, and perhaps fry all the hard drives if
it happened to be the +12V that failed high.

Another way of looking at the problem, is to find a compact
power supply with just enough juice to power one module. Look
for a supplier that makes power efficient designs. Seasonic
does some ATX supplies that are pretty efficient for example
(forward converters, whatever those are).

You could also consider two stage DC-DC conversion. Power a
rack from a kilowatt level 48VDC power supply. Equip each
compute module with quarter or half brick DC-DC power converters.
That is a scheme that is used in the telecom world. But you'll
need some custom design to tie a scheme like that together
(power_good and the like), and the mechanical packaging details
are a PITA.

Using 1+1 redundant AC power supplies, to improve the reliability
of your central supply scheme, would improve some of the faults
with your idea. Another issue you might not have thought about,
is the distribution of high currents down a backplane. You'll
need some decent bus bars to carry enough amps for a rack full
of computers. Remote sense signals connected near the load might
help compensate for losses in the bus bars, but those are not a
typical feature of an ordinary ATX power supply. (ATX power
supplies do in fact have remote sense, but it is not in a
convenient form, like a pair of screw terminals for connecting
up the wires etc.)

Have a look here, and see if a supply from this page could
be packaged inside your compute module. I think having a
small PSU per module will take much less engineering and


I don't know the genesis of your cluster concept, but who
ever made the compute modules must have had a powering scheme
in mind when they made them. What packaging concept did
they have in mind ?


Re: Power suppy that runs several motherboards

On 2 Jan 2006 21:58:46 -0800, "Mike Curry"

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You might save a dozen % efficiency, but this will be
offsest by the cost of such specialized power and custom
wiring harness for the whole thing.  Additionally, it means
if the lone PSU goes down, so do all systems (unless you
want a second redundant unit too and then efficiency drifts
back towards current levels).

First you will need a power estimate for the entire thing.
Next you'll need know if you have anything using the less
common power rails or only 3.3V, 5V, 12V, and 5VSB.  Since
there is no 5VSB needed per sleep modes (presumably, these
will always be "on" or full-off for maintenance?) you might
be able to use a single 5V rail for both. Without the
various power management states you have a simplier need.

Down to 3 power rails, you'd seek an industrial supply or
supplies that can output all 3 and a central power
switch/breaker.  Next you'd have a central distribution
board in a start configuration with the inputs from the
single or multiple PSU and outputs (probably ATX connector
so std ATX extension cords are used) to each board, or a bus
configuration with heavier bus wiring and taps along the
length of it corresponding to each board rack position.

Re: Power suppy that runs several motherboards

Not manufactured, that I'm aware of.


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Re: Power suppy that runs several motherboards

DaveW wrote:
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I had 4 p104 pentiums with a number of p104 interface cards
running of 1 75 Watt powersupply (12 V in) in an instrumented

Re: Power suppy that runs several motherboards

Where can I buy  p104 interface cards?

Re: Power suppy that runs several motherboards

Mike Curry wrote:
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Just google for it, all my docs are located at my former
employer(am retired). -)-)-)

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