When PCGA-CDxx is connected, the computer cannot be set into system hibernation mode even if the HotKey (FN + F12 keys) was pressed.
During battery operation, if the computer is left with PCGA-CD51 connected and the battery is exhausted, the computer tries to go into system hibernation mode by its power management function but will go into suspend mode instead, and the computer is turned off. Sony recommends disconnecting PCGA-CD51 during battery operation.
The symptom is obvious when PCGA-CDxx is connected. However, other popular PC cards may also cause this symptom.