Multiple motherboards from one PSU

[scott.leckie]

Hi there,

I'm building a chassis with multiple mini-ITX motherboards (teeny ~1Ghz
boards from VIA) which, for the sake of this question, use standard ATX
connectors.

These boards are pretty small and I'm aiming to install 4 in a single
chassis.

The power requirements all fall well within a single 350W PSU (yes,
I've counted 3.3v, 5v and 12v requirements) as will their attendant
2.5" disks.

I am assuming that I can splice together 4 sets of ATX connectors from
a single PSU, although I realise that I need to tie the PWR-ON and
PWR-OK lines either to a single mobo or to switches / delay circuits.
I did note a previous posting that suggested using 1N4001 diodes to tie
all the PWR-ON and PWR-OK lines to the PSU so that the first mobo power
up started the PSU, and that this then supplied the PWR-OK signal.

Has anyone else ever done this? Any pitfalls / suggestions /
way-to-gos?

Thoughts appreciated.
Cheers,
Scott

 

[Conor]

Hi there,

I'm building a chassis with multiple mini-ITX motherboards (teeny ~1Ghz
boards from VIA) which, for the sake of this question, use standard ATX
connectors.

These boards are pretty small and I'm aiming to install 4 in a single
chassis.

The power requirements all fall well within a single 350W PSU (yes,
I've counted 3.3v, 5v and 12v requirements) as will their attendant
2.5" disks.

I am assuming that I can splice together 4 sets of ATX connectors from
a single PSU, although I realise that I need to tie the PWR-ON and
PWR-OK lines either to a single mobo or to switches / delay circuits.
I did note a previous posting that suggested using 1N4001 diodes to tie
all the PWR-ON and PWR-OK lines to the PSU so that the first mobo power
up started the PSU, and that this then supplied the PWR-OK signal.

Has anyone else ever done this? Any pitfalls / suggestions /
way-to-gos?

Yes you can do it. Only downfall is if there's a serious fault on one
board that affects the power line, that it may damage the other three
boards so make sure you put diodes on each of the power wires to each
board to give a bit of protection.

 

[skotl]

Thanks Connor.

I could add diodes on the power lines but they would need to be able to
cope with the total draw on each line (10A on 12V?) and I wonder how
often you are going to see such a failure on an ATX / mini-ITX board.

I was looking more to the diodes stopping up/down signals to other
boards, especially as the diodes will drop 0.7v, so want to keep the
usage to a minimum.

Cheers,
scott.