12 volt only for small build

[jmt333]

I am working on a project and would like to use a low-power Supermicro Micro ITX board with an integrated Epyc SoC. This is an upgrade for some equipment I already have, which is based on an Intel Atom SoC.

Existing: Supermicro A1SAI-2750F-O

Planned upgrade: Supermicro  M11SDV-4C-LN4F (Motherboard manual link)

 

This is all very small and very low-power. On my existing setup, I am using a couple of PicoPSUs that connect to an external power brick with a 12 volt barrel jack. The new board that I'd like to use is 12 volt only using the new 8-pin connector. Per Supermicro, the power connector is described as "8-pin 12V DC Power Input (Required for 12V only or 24-pin ATX power)"

If using ATX power instead of 12 volt only, it requires an adapter which, of course, Supermicro is happy to sell me. The problem with that is, as near as I can tell, it would require a second adapter, as well to deliver both power to the 12-volt only connector and the 5v standby, power on signal, etc. and every adapter I can find will convert the ATX 24-pin connector to either 8-pin 12 volt only or the 4-pin ground/standby/power on/power good, but not both.

 

For anyone familiar with 12 volt only, how would you go about trying to deal with this? All of the 12 volt only power supplies I can find are large and usually much higher-power than I need. These won't fit in the cases I have (which are almost the same size as the ITX board itself, and assume an external PSU) and are quite expensive as well as delivering much more power than I actually need. What I'd like to have is an equivalent to the PicoPSU that delivers 12 volt only but barring that, is there any way to adapt a standard 24 pin ATX to 12 volt only and break out the signaling lines in such a way that I can actually use the motherboard?

 

Presumably, I could get the cables I need (24 pin ATX to 8-pin 12 volt only; Supermicro cable for handling other signals) and run them through a breakout board (like this one or similar) and cram the whole mess into my case, but that is inelegant.

 

Is there a better to answer this, or am I way overthinking it and all I need is the 24-pin to 8-pin cable (like this one) and everything should just work with an ATX power supply?

 

Thanks!

- JMT

[BobVonBob]

The 8 pin connector is the same as the EPS 8 pin power connector that would go to the CPU in an ATX system. You don't need an adapter for it. All you need is the 24 pin to 4 pin adapter, which is included with the motherboard.

 

 

Edit: In fact, that's not even a 12VO board. ATX12VO uses 10 and 6 pin connectors. That's just a normal CPU EPS connector and a 4 pin connector for those standby and power on signals.

Edited January 24, 2023 by BobVonBob

[jmt333]

16 minutes ago, BobVonBob said:

The 8 pin connector is the same as the EPS 8 pin power connector that would go to the CPU in an ATX system. You don't need an adapter for it. All you need is the 24 pin to 4 pin adapter, which is included with the motherboard.

Thank you very much for that. I feel like an idiot and was way overthinking things. I have one more question in that case.

 

The PicoPSUs I have found have only 4-pin EPS power. The TDP on this chip is pretty low (45 watts) so a PicoPSU should be able to handle it, but I assume that I should use a 4-pin to 8-pin EPS cable to plug it into the mainboard. Will that work or does that put me too close on the amount of current being pulled over four conductors? Or will just using the 4-pin EPS work, and I can leave four pins empty like on motherboards I'm familiar with?

 

Thanks,

-JMT