HP Compaq dx6100 MT Reference Manual page 142

Removal and Replacement Procedures— Slim Tower (ST) Chassis
15. Reinstall the expansion card cage by aligning the cage with the guide rails on the backwall.
Press down firmly on the cage to secure it in place on the backwall. Be sure the riser card in
the cage is properly seated in the PCI expansion slot on the system board.
Complete the reassembly of the computer.
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