Checked FEC yet?Also, I can't get it to talk to CX4 or CX5 cards at 100 Gbps right now. I mostly blame Mellanox's weird VPI autodetect thing. I'm waiting for fs.com to send me more DAC cables before I really try debugging.
Interesting; I'd missed that. The one cable that's plugged in and accessible right now refuses to link up after running:
mstlink -d 01:00.0 --fec_speed 100G --fec RS