MINISFORUM ESP4B PCIe to 4 × NVMe M.2 Expansion Card. Seems interesting. It uses an
AMD B650/B850 chipset. Which i know has been done before. But it’s interesting seeing a product that appears to be more widely available for purchase. It also doesn’t seem too overpriced for what it is.
@vitabis I saw that you got a PEX88096 switch board working on AM4. Did it basically enumerate once you had the correct host adapter/cabling, or were there any special reset, clock, presence-detect or firmware requirements? I’m trying something similar with a Dell PEX89144 Gen5 switch board.
@itterative Did you ever resolve the issue where your PEX88096 showed correctly in lspci but none of the downstream GPUs appeared? I’m preparing a PEX89144 project and would really like to know what the final cause was.
@AllenLYTC3249 I saw your work modifying the PEX880xx SPI configuration and your comment that it might apply to Gen5. Have you done anything yet with PEX89000/PEX89144 hardware? I’m working with Dell PEX89144 switch boards and may eventually need to understand their existing Synthetic configuration.
Well it depends on what you want to do with it. More USB ports on the lekuo card is nice. But i am not a fan of the six pin power and the sata ports. And the ESP4B comes with a heatsink.
Thank you, that’s helpful. Could you share links or model numbers for your switch board and host adapter/cables? Did it work with the switch firmware as supplied, and was x8/x8 needed even with only one upstream connection?
Are there any solutions which work with a standard ATX motherboard in a standard ATX case? I see options for using risers from M.2, but nothing inside a standard case that doesn’t involve a hacksaw.
Do you have any images of this PCIe switch that you can provide? In fact, many OEM-produced PCIe switches do not follow standard pinout definitions for connections; they use their own custom wiring sequences.
Regarding the modification of the PEX89000 SPI configuration you mentioned, I think you first need to confirm whether your PEX89000 switch operates in BSW mode (Base Switch mode) or iSSW mode (Internal Synthetic Switch Mode). When running in BSW mode, you can indeed modify the SBR configuration using Broadcom’s SDK, similar to the PEX88000 chip referenced above. However, if it works under iSSW mode, this configuration method will not apply. The Internal Synthetic Switch Mode is generated via XML configuration files supplied by Broadcom, and these files are protected under NDA and cannot be easily obtained.
Moreover, to my knowledge, all current PEX89000 series chips have Secure Boot enforced. You must flash firmware files generated with the manufacturer’s keys into the SPI flash for the chip to pass verification and load the firmware. If the keys are invalid, the chip will refuse to boot.
All of this is quite complex. If you purchased the PCIe switch through official channels, I recommend contacting the manufacturer for technical support.
