Game titles using older SDKs (before 2.7.1) that never supported GPU accelerated PhysX are no longer included in the PhysX System Software that is included with the Public combined GPU driver. These games will need the NVIDIA PhysX Legacy System Software install on top of the combine GPU drivers.
You can download the NVIDIA PhysX Legacy System Software here: http://www.nvidia.com/object/physx-9.12.1031-legacy-driver.html
Game titles using older SDKs:
-Clive Baker's Jericho
-Gears of War
-Medal of Honor Airborne