Routing on PCIe bifurcation points PCIe Bifurcation Routing
Routing on PCIe bifurcation points PCIe Bifurcation Routing
I’ve used every PCIe port on my Asrock Taichi X399 board, but adding another x4 device is still a challenge. I discovered the board can handle PCIe bifurcation, though I’m not clear on the wiring details. My goal is to divide the last x8 slot into two x4 slots. I haven’t found a direct x8→x4 splitter, only 16x→x8 adapters such as the Supermicro RSC-R2UW-2E8R. I’m wondering if a similar approach could work—since the physical slot is 16x but only x8 technically exists there. Would the splitter simply take the first half of the connectors and send them to one port, and the second half to the other? I don’t understand how routing functions for an x16 slot that’s actually x8 at the hardware level.
You might find an adapter that changes a m.2 port to a PCIe X4 connection... here are the top results I see on eBay for this: https://www.ebay.com/itm/174675173638?ha...SwlEhgNxAT Another option is https://www.ebay.com/itm/402802503767?ha...SwSLtgf4mF a version with an integrated flat flex cable: https://www.ebay.com/itm/273986300024?ha...Sw3gJdaNwb and it connects directly to an X16 slot: https://www.ebay.com/itm/273986294382 The power supply is included to bring in 12V for the PCIe port, since m.2 only supports 3.3V. If you use a PCIe X4 riser cable with its own 12V input, that won't work.
I believe you're after the RSC-R2UU-2E4R model, which supports splitting x8 into dual x4 with x8 physical connectors.
I initially had the same idea until I discovered the RSC-R2UU-2E4R solution. It seems to handle things directly. Think about combining a Supermicro dual M.2 splitter with an M.2 to x4 adapter. Seemed a bit overwhelming at first, but really helpful tip—thanks!