Hey guys,
I recently did a ton of looking into the subject of DOMs and specifically compatibility between Supermicro SuperDOM ports and Innodisk DOMs. I *think* I finally figured it out, however I'm not going to swear to this, because I haven't bought a DOM to test yet.
My understanding is that SuperDOM ports do *NOT* provide power on the 7th SATA pin. The motherboards from other vendors that do that tend to have a jumper nearby that you need to switch to either +5V or GND, and they do not auto-sense that a DOM needing power was inserted. I haven't seen a SM board with that kind of configuration, I've seen it on Intel and maybe some other boards.
Instead, SuperDOM ports provide power on what is called the 8th SATA pin. This isn't really a "pin" at all, but a little pad on the outer ring of the SATA connector. Innodisk sells different DOMs that support 7th pin power, 8th pin power, and/or external power, so the 8th pin power DOMs should be compatible with SM boards. If you look closely on a compatible DOM you can see the little metal pieces on the sides that look like tensioners to hold the DOM in the SATA port:
Those little prongs touch the metal pads on the inside of the SuperDOM port, which you can just barely make out in the bottom circles of this picture:
The issue I've found is that the super cheap Dell DOM all over eBay is only compatible with 7-pin power, not 8-pin power, so it doesn't work in SM boards. I saw at least three cases, not all on this forum, of people saying that specific model did not work in their board. Conversely, if you find an Innodisk DOM that supports 8-pin power, it should work in a SM board just fine. I haven't tested it yet myself, however one great clue can be found in this article:
https://www.servethehome.com/innodisk-satadom-sl-3me3-v2-128gb-benchmarks-review/
That shows an Innodisk DOM working fine in a SM board, but it's a different part number from the cheap Dell part. If you check the specs on Innodisk's site, this part number supports both 7-pin and 8-pin power, so while it's not a slam dunk, it does lend some support. In addition, if you look very closely at the 2nd picture in that article you can see the metal tab on the side of the DOM connector, just like my first photo above. It's a little easier to see on the left side in that pic.
Anyway, I'm fairly sure this is the answer, but until I buy a DOM compatible with 8-pin power and *not* compatible with 7-pin power and test it in my SM board I can't say 100% sure. Also, that's one other thing to watch out for, some DOMs support all 3 methods of power delivery, some only support 2. So some DOMs out there can only support 7-pin and 8-pin power and can *not* support external power cables. This is even true of some models that have an external power connector. The PCB's are all the same apparently, but some can *not* actually be powered from that side connector. So if nothing else, before buying a cheap DOM on eBay, make sure to look up the Innodisk spec sheet and make sure it supports the right kind of power delivery. Ideally (I think?) Pin-8 power and external cable would be the best combo for SM, since I believe 7-pin power is useless on our boards.