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Top-level
So unfortunately, it looks like there isn't enough clearance in the T620 case for this card's SATA connector and even a right angle connector. @warthog9 tried to talk me into replacing the connector on the board with a right angle connector, but I like the idea of just soldering a pigtail onto the mPCIe card, because SATA is literally just two pieces of twinax for transmit and receive! 24 comments
@ewenmcneill that's absolutely it. Three grounds to help keep the impedance of the two pairs controlled and isolated from each other. It's extremely common on high speed connectors to weave signal pairs with grounds between them. I.e. go look up the pin out for PCIe slots. https://pinouts.ru/Slots/pci_express_pinout.shtml @ewenmcneill there's a non-standard convention that vendors like Supermicro uses to optionally inject 5V on one of the three ground pins to power SATADOMs, which are tiny SSDs that hang right off the SATA connector on the motherboard. @kwf @ewenmcneill Wait... THAT'S how they're powered?! Does the motherboard detect a short and not inject power as appropriate, or are these dedicated DOM / non-standard connectors? @attie @ewenmcneill They must have some kind of detect logic on the motherboard, but they're fully functional normal SATA ports. I think on SuperMicros they're conventionally the one yellow port that has power.  Yeah, so as reported online and expected, normal right angle SATA cables aren't even close to low enough to let us put the cover back on the case. Good sanity check I'm making before doing the cursed is making sure everything works BEFORE I start cutting on it. That way I can know I'm really the one who killed it when it stops working. 😈 The connector is too tall you say? Well that's fine. Nothing a little hot air and a soldering iron can't fix. #xp Now that we have a SATA cable, the next thing we need for a hard drive in here is a SATA power cable. Luck would have it I have a spare SATA power cable laying around from a dead power supply. And 2.5" SATA hard drives are nice in that despite the 15 pin connector having positions for 3.3V, 5V, and 12V, the only required voltage for 2.5" disks is 5V! And there's an internal USB port I don't care about RIGHT THERE! ✅ SATA data Now we need somewhere to mount the drive. 24 gauge sheet metal is wonderful; it's like the hot glue of the computer modding world. I don't know if this was the original intention for the standoffs I'm using. It's sure exactly-the-right-size for it... The highest density 2.5" hard drive you can get in the thinner 7mm form factor, a rummage through my little bin of tiny computer screws, and I want you to brace yourself for the unholy abomination that is about to grace your screen. Kind of a bummer that the HDD activity on the mPCIe card doesn't report out to the activity LED on the front panel. I feel like further hacks may need to be considered here for that. @ExplodingLemur You can also get 4TB QVO SSDs in 7mm SFF, but I wasn't real thrilled to drop $250 on an SSD for this tomfoolery. @ExplodingLemur I'm paying $110-$160 a piece for these 2TB M.2s I'm playing with. @kwf @ExplodingLemur from the eBay listing you posted the other day, it looked like these 2T SSDs are used pulls from other gear, yes? @kwf TBH other than the white silicone, I’d probably accept that as “factory stock” if I just glanced at it. (With a black mechanical blob holding the SATA cable in place, it’d just look like a “chip on board” setup.) Someone should persuade Chinese factories to make M.2 male to SATA cable (omitting the socket) for this “low profile” use case; there are already far weirder A to B options available from China…. 🤔 |
Gregory's Server
@kwf TIL.
There’s at least 7 contacts in the SATA connector though, which is rather more than 4. Are the rest just “yeah, we put in a lot of ground connections for signal integrity”? 🤔