Hi Stanley,
The applicable FW depends on the PSID/BoardID of the HCA card.
Have you installed the MFT (Mellanox FW Tool) on the ESXI server?
If so, to get the PSID of the HCA card:
#/opt/mellanox/bin/mst start
#/opt/mellanox/bin/mst status -v
#/opt/mellanox/bin/flint -d <mst device> q
You will see a field label as PSID.
If you could please provide in order to point you to the correct FW.
If you do not have the MFT tool installed, you can download it from the following link:
http://www.mellanox.com/page/management_tools
NOTE: Make sure you download both "mst" & "mft" vibs and choose the accurate kernel (vmk or native).
Sophie.