Roger Hayter wrote:
Chris Green wrote:

Roger Hayter wrote:
If I get one of those semi open frame type SMPSU's I could put it
inside the PSU case as that only contains the one 120mm fan atm.

That's a *lot* of power for a fanless Atom based board. My full-blown
desktop machine with a (6th gen, or maybe even 5th gen) I5 and three
disk drives only consumes 18 watts when idle and maybe 25/30 watts
when working hard. That's a maximum of around 3 amps at 12 volts.

I doubt very much if you need anything like 7 amps.

A significant component is the starting current for the drives. If
this is not specified then you really need an oscilloscope to check.
Even laptop drives may draw twice their rated current when operating.

So stagger the startup. Most PSUs will handle short term surges more
than their rated output anyway and/or the output will droop a bit as
the drives spin up.

If the output droops the CPU may reset or generate unrecoverable errors
causing a reboot. Although the drives may stay running and therefore
the process not be infinitely repeated, this is a bad idea which could
cause data corruption or electronic harm of some sort e.g. to voltage
regulators.

Possibly, but not very likely as it's a 12 volt supply and the CPU
etc. probably all run at 3.3 volts, that leaves *lots* of headroom for
the 12 volts to dip a little without having any effect at all on the
electronics.


Staggering the drive start up is easier said then done unless the
hardware is designed to do this.

True, it was only a possible idea.

I *still* think 12 volts 7 amps sounds a crazy amount of power for a
fanless Atom board (even including some disk drives). It's something
like three times as much power as my I5 desktop with four disk drives
in takes.

--
Chris Green
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