Immediately after my TrueNAS CORE server power supply caught fire, I replaced it with a spare power supply I had on hand. This replacement had one annoyance: it had fewer SATA power connectors. As a short-term fix, I dug up some adapters from the older CD-ROM style power connectors to feed my SATA drives, but I wanted a more elegant solution.

The ATX tower case I used for my homebuilt server had another issue: it had only five 3.5" hard drive bays for my six-drive array. At the moment it isn't a problem, because the case had two additional 2.5" laptop sized hard drive mount points and one drive in my six-drive array was a smaller drive salvaged from an external USB drive which fits in one bay. The other 2.5" bay held the SSD boot drive for my TrueNAS CORE server. I did not want to be constrained to using a laptop drive forever, so I wanted a more elegant solution to this problem as well.

I found my elegant solution for both problems in a Rosewill RSV-SATA-Cage-34 hard drive cage. It fits four 3.5" drives into the volume of a trio of 5.25" drive bays, which is present on my ATX tower case and currently unused. This would solve my 3.5" bay problem quite nicely. It will also solve my power connector problem, as the cage used a pair of CD-ROM style connectors for power. A circuit board inside this cage redistributes that power to four SATA power connectors.

First order of business was to knock out the blank faceplates covering the trio of 5.25" bays.

Quick test fit exposed a problem: the drive cage is much longer than a CD-ROM drive. For the case to sit at the recommended mounting location for 5.25" peripherals, drive cage cooling fan would bump up against the ATX motherboard power connector. This leaves very little room for the four SATA data cables and two CD-ROM power connectors to connect. One option is to disconnect and remove the cooling fan to give me more space, but I wanted to maintain cooling airflow, so I proceeded with the fan in place.

Given the cramped quarters, there would be no room to connect wiring once the cage was in place. I pulled the cage out and connected wires while it was outside the case, then slid it back in.

It is a really tight fit in there! Despite my best effort routing cables, I could not slide the drive cage all the way back to its intended position. This was as hard as I was willing to shove, leaving the drive cage several millimeters forward of its intended position.

As a result, the drive cage juts out beyond case facade by a few millimeters. Eh, good enough.

[UPDATE: I learn there exist products with a similar concept for small 2.5" (laptop) form factor drives. Athena Power BP-15827SAC packs a whopping eight 2.5" SATA drives into the volume of a single 5.25" CD-ROM drive bay. All eight must be thin 7mm drives, though. To accommodate thicker drives, Athena Power also has six-bay and four-bay versions of the same idea, and naturally there are other vendors offering similar executions.]