The fan does nothing over 20-30 mph driving speeds, it is there the allow the air to flow when the engine is stationary to stop it over heating.
If you drove continuously with the fan not working the car would easily keep itself cool, if it was set up properly!!
I'd say the head gasget going is more to do with the fact that the engine is running on a standard engine map and is probably running extremly lean on boost. You need a good map to make this a reliable car!!
