Doing some Googling turned up this:
http://moca.espresso.gr.jp/wiki/wiki.cgi?page=InfiniBand
(translate.google.com does ok with it)
That seems to indicate the card is an MHGS18-XTC. Looking at the Mellanox firmware table and reading the specs there vs what's the specs on the Cisco site, it seems like it could also be a MHES18-XTC:
- http://www.mellanox.com/page/firmware_table_IH3Lx
- http://www.cisco.com/en/US/prod/collateral/ps6418/ps6420/ps6428/product_data_sheet0900aecd8042cf46.html
Looking at the card itself, do any of the stickers printed on it have useful info? The "Revision" thing can sometimes be useful too. If I had to guess, I'd go with the model mentioned on that japanese page as a first go.
How many cards do you have, and how much of a problem would it be if one of them dies? (eg badly wrong firmware) It could come down to this.