Anything is possible with PCIe but some configs are not getting prettier, or as you state, very sensible ones money-wise. The PCIe2x1 bus speed, even bumped up to unsupported PCIe3x1, is a substantial limiting factor for one NVME, and that wouldn't be less so for 2 NVME's or even more add-ons. Also, to my knowledge the FFC connection limits power output at 5W, so you will probably need extra power too with more and more devices added. Again some extra cost.
Extra cost? Probably if you want anything other than 5v. For 5V only do what the official M.2 HAT does and draw from the 5V GPIO pins not the FFC. The limit there is what the PSU can provide.
As for other concerns, I've been running a CM4 based NAS with a PCIe switch (3 way ASM1184e ), 2 x SATA cards (ASM1062), and a USB 3 card (VL805). The performance limit is the network (2.5Gbps to one PC, 1Gbps to everything else). The only time I really notice a performance hit is copying between SATA devices or between SATA and USB3.
Yes, the single lane is a limit but if only one device is active it gets almost all the available bandwidth with a little more latency compared to when connected directly.
Statistics: Posted by thagrol — Wed Sep 03, 2025 10:51 pm