TLDR; Is it safe/possible/sensible to reuse the 12v and 5v connections from an ATX 24 pin connector on a dual rail PSU?
I’ve been looking to build a ZFS backup target using my old 4TB drives, SAS HBA, and an SBC with a PCIe slot but just need to sort out the power supply. Given that all the components fit into the same footprint as a 3.5 HDD I was thinking of a Flex PSU which looks about the same length and slightly narrower so the whole thing would fit in a cheap drive rack for portability.
Currently looking at a DPS-350AB-12 as I’ve only heard good things about Delta power supplies and you can find them cheap 2nd hand.
The plan is to get two extension cables, one for the 6 pin to solder a 12v barrel connector for the SBC which in turn powers the HBA, and the one for the 24 pin which I’d solder the SATA connectors to, and a switch on the sense pins to power it up without a motherboard attached.
What I’m not sure about is whether the supply being dual rail complicates any of this, looking at the pinout for a 24 pin it looks like there’re two 5v and 12v wires each which I’d assume are connected to each rail so the load would be distributed evenly?
I’m also not sure whether the supply would agree with this arrangement as I’ve used a paperclip to use the SATA connectors of a power supply before but not sure if the 24 pin has extra requirements, although hopefully not an issue here apparently older models won’t supply 12v unless there’s 5v load too?
It looks like the supply should be able to cope with the extra current during spin up as the drives’ datasheet states a peak of 2.16A DC is needed, so 17.28A for the drives and 3A for the SBC (it looks like the HBA uses a max of 1.81A which would come out of the SBC’s 36w budget) which is just within the max 12v output of 21.6A according to this test
