Philip
Mellanox does not lock its ports or require you to buy Mellanox cables. In fact, we constantly test third party cables in conjunction with our switches to ensure compatibility. The value proposition with Mellanox cables is that our cables are manufactured to very high standards, are certified to work flawlessly and have additional capabilities such as being able to identify link speed mismatches when you run a query from the system.
We are still waiting for the mstdump from your system. This will help us identify where the issue lies and why this optic is reporting 10GE speed to the FW. Please send us the mstdump and we will do our best to resolve this issue.
Thanks
Anand Rangaswamy