Hello Raphael,
Thank you for posting your inquiry on the NVIDIA Networking Community.
The ConnectX-6 VPI adapter supported PAM4 and NRZ. See the following link for all Features available for the ConnectX-6 adapter → https://docs.mellanox.com/display/ConnectX6Firmwarev20292002/Changes+and+New+Feature+History
To connect the cable to the ConnectX-6, you need to use the MAM1Q00A-QSA28 module as mentioned in the f/w RN (Search for MAM1Q00A-QSA28) → https://docs.mellanox.com/display/ConnectX6Firmwarev20292002/Firmware+Compatible+Products
Thank you and regards,
~NVIDIA Networking Technical Support