Search for a PCIe port divider that eliminates the need for riser cables.
Search for a PCIe port divider that eliminates the need for riser cables.
Imagine you have a PCIe 1x card and a PCIe 4x port. The card isn’t using any lanes, leaving three unused ones. If you could convert them into an M.2 slot, would there be a solution? Your 16GB Optane NVMe drive also uses just two lanes. There seems to be no standard device that directly assigns those two lanes to an M.2 interface.
Only motherboards designed for this purpose can achieve it. Usually, inserting a 2x NVMe card turns off USB or SATA connections on the board instead of using PCIe lanes. It’s unlikely you’ll discover a method. You likely have a 16x, 8x, 4x, or 1x slot in your expansion cards, with any extra lanes simply unused. While a custom "secondary south bridge" chip might be possible, it wouldn’t fix the issue even if found.
This configuration swaps the PCIe expansion slot and distributes eight lanes to each position, even though the physical slot remains a 16x slot. The Supermicro RSC-R2UT-2E8R 2U RISER PASSIVE model supports Gen 2-PCIE X16 to 2X PCIE X8 interfaces and indicates BIOS compatibility is needed.
It seems the system supports x2, matching the performance of my Optane stick and a PCIe x2 card. The device comes with a B+M key. Also confirmed, it's running 57C, positioned right next to my CPU cooler without any heat sink.