It seems I have the same problem as
@cromo,
I recently was looking for a Mellanox to put inside my Lenovo m920q. While browsing, I found the ConnectX-4 model number MCX4121A-ACAT ConnectX-4 Lx CX4121A.
it seems the same price and newer model while supporting sfp28. Therefore, I got this ConnectX-4 via eBay.
When I tested it in a Supermicro server, the ConnectX-4 functions and works perfectly. Also, It is being recognized by Ubuntu and takes a DHCP lease.
However, when I put it inside the m920q, the Tiny won't boot, it does not post video. Its lights power on, and the CPU fan doesn't start.
So, the m920q doesn't work only when the card is installed.
On the contrary, if I put any other PCIE card in there, it works fine.
For example, the SAS 9207-8e card works fine in there.
I was just wondering
@cromo if you have any progress, with yours?
Brainstorming? Is it probably incompatible for any reason? Or is the PCIE version not supported? This card seems to be PCIE 3.0 and x8. It should be supported in this Lenovo. Probably the card is damaged in some way? I don't know.
EDIT: I also tried:
PRSNT PIN connecting hack but it did not work.