Reddit project shows flexible PCIe bifurcation riser design
A Redditor “thepromiseman” from homelab has showcased a PCIe adapter designed for low-profile GPUs that also adds two M.2 slots. The card works as a riser that converts a half-height PCIe device into a full-height form factor, while using unused PCIe lanes to provide additional NVMe storage.
The concept relies on PCIe bifurcation, which allows a single x16 slot to split into multiple lane groups such as x8 plus x4 plus x4. In this setup, part of the bandwidth is allocated to the GPU, while the remaining lanes are routed to the M.2 slots. Without bifurcation support at the motherboard and CPU level, the adapter will not function correctly.
This type of solution is useful for compact systems such as mini-ITX builds or home servers where PCIe slot availability is limited. Users can install a low-profile GPU or NIC (no one says this has to just a GPU) while also adding high-speed storage without requiring additional slots. Some users report using similar adapters in NAS or virtualization setups to expand NVMe capacity.
Source: Amazon/Reddit
The approach is similar to designs already used by GPU vendors, where M.2 slots are integrated directly onto graphics cards. The most popular example is the ASUS DUAL SSD series .
Source: Amazon
In Amazon reviews I found a picture of someone running two similar adapters, both using half of the available PCIe lanes. Effectively this turned one x16 slot into a quad M.2 config. Of course, at this point it will make more sense to just buy a quad adapter, but this perfectly shows what this device does.
Source: Reddit
