Intel Express 100BASE-TX User Manual page 45

You can install up to six 100BASE-TX Host Modules in an
unmanaged stack to provide you with 144 ports per Fast Ethernet
segment. In a managed stack, you can install up to five host modules
to provide you with 132 ports per Fast Ethernet segment.
For instructions on how to install a 100BASE-TX Host Module in the
hub, refer to the documentation that shipped with your host module.