Supermicro X9SRW-F small riser mounting adapter (#P24)

More fun with the Supermicro X9SRW (and we’re still not done yet!)

The two X9SRW machines that I got had the same CPU and RAM situation, but one of them was in a 815 (1U) case, and the other one still is in a 825 (2U) one. I scrapped the noisy 815 for my board and allocated the more spacious 825. Fans are not the only thing that differs, though, as the added height also caused Supermicro to exchange the riser card for a different one. While the top riser is just an angled PCIe x8 connector (high up to make room for some heat sinks underneath), the bottom one is a WIO type that distributes 32 lanes in total. Oddball shape and connectors, but there are quite a few different riser cards available (for a pretty penny, I have to add). Spacing is also not conforming to PCIe (well, ATX?) standards.

This is how the thing looks like:

This is a deliberate decision to make full-sized cards fit on the bottom riser while keeping the riser design simple. The top riser only has space for low profile cards, but it also cuts into the I/O panel area and the air guide that is not present on the photo.

Bot risers are screwed into place and the mounting bracket is then fixed to the back of the case and the crossbar behind the drive cages.

For the 815, using the RSC-R1UW-2E16 riser is an obvious choice. It’s an 1U compatible design that offers 2x PCIe x16. That’s all the lanes that are available in all of the space that is available. Great.

For the 825, the RSC-R2UW-4E8 was chosen. Now this is a 2U riser, but since there’s only 32 lanes, they made it into a 4×8 design. This fits my requirements with 3 or 4 cards best, but others might want 2×16 with one slot of spacing for heat sinks or 16/8/8 solutions. I could even use use risers with single x4 or x1 slots due to my 3U case (if bifurcation works down to this level), but that’s not something Supermicro offers nowadays.

So when I swapped risers as shown previously, the 825 got a small 1U riser in exchange. Problem is: There is a 2U mounting bracket that fits 2U cards, there’s an obsolete 1U mounting bracket that fits 1U cards, but there’s no way to stabilize an 1U card in a 2U case.

3D printing to the rescue, once again…

RSDOC, STL, thingiverse

Straight forward design – v1 was just a 0.5mm slab that I used to check my alignment and sizing, v2 gave the thing some rigidity and I fixed hole sizes by a tenth of a millimeter (you Yanks can go eff yourselves, I’m not going to convert this into fractions of standardized thumbs, feet, or any amount of barleycorn). YMMV depending on your 3D printer settings – the hole sizes are pretty close to 5.5mm and 7.0mm, so in case they are not perfectly round or a tad too small, using a standard drill is the easy way to make it fit.

This is how it’s mounted to the main metal bracket, it’s basically a press fit. Four screws secure it in place on this side; this is just the screw holes that were used with the 2U riser. The riser on the other side has a different set of mounts, there are no shared threads.

The 1U riser is then screwed on top of it. Note that the right screw near the Supero logo can have arbitrary length as the x8 riser on the other side is much shorter and they wouldn’t collide. The left screw however needs to be pretty short, as it does move against the metal frame, bending the riser out of alignment. As all of the existing threaded inserts on both sides are of the UNC #6-32 type (ugh…), I’ve kept that crap for my custom screw holes. Yes, I admit it, coarse threading might be superior on layered 3D printing materials compared to regular metric threads.

Fits nicely, does not stabilize the entire thing like a metal adapter would do, but it does the job. Once cards are inserted, it’s also fixed in place a little more due to the card bracket being clamped to the back panel as in every regular PC. The adapter also provides some electrical insulation for when one presses against the riser card (Supermicro also provides a thin plastic sheet that does not cover 100% of the exposed metal parts)

This is the entire thing assembled and almost ready to go – three mounting screws of the main metal bracket are still missing. I only realized that when I heard these move around during heaving it into the trunk of my car ;)

The 825 is now in the hands of its rightful owner, and I’m still onto something with my X9SRW. Farewell, little Ivy compatible board…


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