A computer system comprises a plurality of shelves. Each shelf has a carrier for removably receiving a plurality of information processing modules and a switching module. Each shelf also has an interconnection member for providing connections between the information processing modules and the switching module. The shelves are logically connected into a plurality of stacks, the switching modules of the respective shelves in each stack being interconnected in a logical stacking configuration. The computer system further comprises a shelf having a carrier for removably receiving a master switching module, wherein the master switching module is connected into each stack as a common master switch for all of the stacks.