Hi all, Plugged in a W3680 in a 4,1 today. Had to do the firmware update, of course, and that brougt me to the netkas forums. There was this thread: http://forum.netkas.org/index.php/topic,852.msg16072.html#msg16072 It says: "IMPORTANT: If you have updated your 4.1 Mac Pro to a 5.1 using this utility, DO NOT install the Mac-OS 10.8.2 supplemental update. I just did and my machine refuses to boot." Can anyone confirm this problem? I don't dare upgrading the OS at the moment. UPDATE: A number of people (see below), including myself, have successfully installed the update without issue.