This section is about building and modifying hardware: soldering and custom electronics, writing the firmware that runs on them, and pushing PCIe outside the case using PCIe switches and USB4 bridges. PCIe is the fast connection inside a computer that links things like graphics cards and drives.
These posts cover hands-on projects: flashing and writing custom firmware, wiring up boards, and getting external PCIe devices working over PCIe switches and USB4 or Thunderbolt links.
A tri-mode adapter lets any bay take SAS, SATA or NVMe — real flexibility, and the reason U.3 backplanes exist. What it does not advertise is that your NVMe drives stop being NVMe drives: they arrive in Linux as SCSI disks on mpt3sas, queue depth 128, sharing one tag pool and one x8 uplink. Two Gen4 drives saturate the card. A single Gen5 drive is already past it. Whether that trade still makes sense in 2026, and why the universal bays belong to the backplane rather than the controller.