Instructions
Open the Internet browser on your computer and go to the PS3 System Update History at us.playstation.com/support/systemupdates/ps3/history/index.htm. This page shows all of the firmware versions and the dates they were released.
Turn on the PS3 console with no game inserted.
Select "Settings" and choose "System Settings."
Select "System Information" to display the current firmware version. Check the firmware version and release date information against the information on the website. If they match, you have a PS3 with the official firmware. If they don't match, you have a PS3 with custom firmware.