Gen5 hardware is S210, X410, NL410, X210, and HD400. Gen6 has not been released yet. The 40GB NICs are referring to an external interface, not IB interfaces although in Gen6 IB will have an ethernet option. They would be a very recent hardware upgrade for Gen5 nodes so it is not likely that it applies in your case. Here is the product support bulletin on Gen6:
That looks like it may be an internal link so you may not have access to the information in it. These should work for you though.
Isilon F800 Support page: https://support.emc.com/products/41848_Isilon-F800
Isilon H600 Support page: https://support.emc.com/products/41847_Isilon-H600
Isilon H500 Support page: https://support.emc.com/products/41846_Isilon-H500
Isilon H400 Support page: https://support.emc.com/products/41843_Isilon-H400
Isilon A200 & A2000 Support page: https://support.emc.com/products/41844_Isilon-A200_A2000