Hello,
So cable interop/detection usually happens at the firmware level and as such interop issues can arise unfortunately like your seeing.Mellanox does not test interop with all 3rd party cables and HCA/Nics.Keep in mind that firmware/drivers and actually programming on active cables can change over time and issues can arise even with best efforts.What I suggest is to use the Mellanox approved cables listed below per http://www.mellanox.com/related-docs/user_manuals/Mellanox_approved_cables.pdf document.Hope this helps.I also just updated my reply with a link to our comprehensive cable matrix below
http://www.mellanox.com/page/cables?mtag=cable_overview#table
Mellanox breakout cable P/Ns (passive copper):
MC2609130-001 (1m)
MC2609130-003 (3m)
MC2609125-005 (5m)