For SIOM, Ultra, and microLP 25G cards, they will work in the respective systems and MBs with SIOM, Ultra, and microLP slots. For standard cards such as AOC-S25G-m2S, it has an NC-SI connector which requires MBs with the corresponding NC-SI connector. If MB does not have NC-SI connector, the card will work as a generic 25G card but the NC-SI function will not.