Help with SuperMicro and Mellanox ConnectX-4-based NIC - no network interfaces are appearing?

I have a SuperMicro server, and I've just installed a new SIOM (proprietary SuperMicro form factor) network card - AOC-MHIBE-m1CGM.

From the specifications, this seems to be based around the Mellanox ConnectX-4 chipset.

The SuperMicro website mentions it can do either Infiniband or 100Gbps Ethernet.

(I'm pasting screenshots, because the box doesn't have network connectivity yet, and I'm doing this over IPMI)

Anyhow, when I check ip addr listed, I don't see the 100Gbps interface come up (either on Infiniband or Ethernet):

https://i.imgur.com/M3B4rYa.png

If I check dmesg output, I do see "mlx" mentioned:

https://i.imgur.com/TwUorXY.png

mlx5_core 0000:21:00.0: firmware version 12.21.0000 mlx5_core 0000:21:00.0: 126.016 Gb/s available PCIe bandwidth (8 GT/s x16 link) ... mlx5_core 0000:21:00.0: Port module event: module 0, Cable plugged mlx5_ib: Mellanox Connect-IB Infiniband driver v5.0-0 

Also - if I check lspci, I don't see Mellanox mentioned at all.

Any ideas what's going on? Is there something wrong with the card, or do need to do something special to get it to work?