There appears to only be one model Phenom II X940 CPU and it fits in the S1g4 socket. See the links below for upgrade info. on the S1 socket mobos and the X940 CPU. The X940 is a 45w CPU and not all mobos will support this higher power consumption CPU.
Important: You would need to have a mobo BIOS that supports the X940 model for it to work in your PC however.