Since you are using a 5y old Mellanox adapter ConnectX-2, which is now EOL (end-of-life), then first thing you need to do is to line up with the “compatible” components.
The only combination of that I found that I think will still work properly with ConnectX-2 is:
O.S. - Win7/Win8.1/Win2008/Win2012(R2)
Driver: WinOF v4.80.5000 (can be downloaded from Mellanox website / Archive)
Adapter: ConnectX-2 fw v2.9.1000
can be found in https://www.mellanox.com/page/firmware_table_ConnectX2IB
More on that you can find in Mellanox website link: http://www.mellanox.com/related-docs/prod_software/MLNX_VPI_WinOF_Release_Notes_Rev_4.80.pdf
As you can probably see - Win10 & Win2016 will not work properly with ConnectX-2 fw & mellanox driver
Now, assuming that you managed to put together the suggested combination - next would be doing "optimization & performance-fine-tuning"on the system (Driver, fw parameters), as indicated in cahpter 3.8 of the WinOF v4.80 user manual: http://www.mellanox.com/related-docs/prod_software/MLNX_VPI_WinOF_User_Manual_v4.80.pdf
If all tuning is done properly then run : “Ntttcp” test between 2x CX-2 adapters to ensure you get network-bandwidth around ~9Gb/s
if this is achieved this performance, then you are good to start you other tests
Hope this helps