It’s being used primarily as a PCIe switch, the utility of which is dynamic bandwidth distribution of a larger number of downstream PCIe lanes.
Further discussion, since I’ve looked for this specific component several times previously …
To connect NVMe directly, without a switch, requires 4 lanes per blade. Likewise, a SATA controller typically requires at least 1 dedicated lane. A PCIe switch like this requires only 4 (or sometimes 8) lanes upstream but can enumerate 16+ additional lanes downstream.
You could use this expansion card to, for example, add switched PCIe lanes to a mini-ITX mobo via one of its unswitched (direct to CPU) m.2 slots to multiply the number of PCIe/NVMe/USB/SATA devices it can have connected at once.
What’s unique about this is that aside from the actual total SoC PCIe lane/bandwidth limits and the latency added to anything connected downstream, discrete chipset PCIe expansion hypothetically allows an arbitrary amount of extensibility within nearly any footprint.
The likely intended use case for this component is GPU farms, where async I/O at x4 to an arbitrary number of PCIe devices can minimize delay between batch cycles up to the capacity of the CPU, especially compared to the common existing solutions like USB-linked x1 PCIe expansion boards which have limited throughput by comparison.
The M.2 NVMe slots, SATA and USB on this board might suggest an emphasis on storage and peripherals, but that’s just what the b650 chipset hosts downstream. M.2 Oculink adapters to x16 redriver boards are ubiquitous and cheap, and 4 of those plus this expansion card would allow an AM5 consumer CPU to be used more like AMD’s enterprise server platforms (which provide many more unswitched PCIe lanes by default) but at a fraction of their price.
It’s being used primarily as a PCIe switch, the utility of which is dynamic bandwidth distribution of a larger number of downstream PCIe lanes.
Further discussion, since I’ve looked for this specific component several times previously …
To connect NVMe directly, without a switch, requires 4 lanes per blade. Likewise, a SATA controller typically requires at least 1 dedicated lane. A PCIe switch like this requires only 4 (or sometimes 8) lanes upstream but can enumerate 16+ additional lanes downstream.
You could use this expansion card to, for example, add switched PCIe lanes to a mini-ITX mobo via one of its unswitched (direct to CPU) m.2 slots to multiply the number of PCIe/NVMe/USB/SATA devices it can have connected at once.
What’s unique about this is that aside from the actual total SoC PCIe lane/bandwidth limits and the latency added to anything connected downstream, discrete chipset PCIe expansion hypothetically allows an arbitrary amount of extensibility within nearly any footprint.
The likely intended use case for this component is GPU farms, where async I/O at x4 to an arbitrary number of PCIe devices can minimize delay between batch cycles up to the capacity of the CPU, especially compared to the common existing solutions like USB-linked x1 PCIe expansion boards which have limited throughput by comparison.
The M.2 NVMe slots, SATA and USB on this board might suggest an emphasis on storage and peripherals, but that’s just what the b650 chipset hosts downstream. M.2 Oculink adapters to x16 redriver boards are ubiquitous and cheap, and 4 of those plus this expansion card would allow an AM5 consumer CPU to be used more like AMD’s enterprise server platforms (which provide many more unswitched PCIe lanes by default) but at a fraction of their price.