Since my previous post regarding the Gateway GM5478 CPU fan roar and subsequent restart issue has already received nearly 90 comments, I figured I would add a new post to provide a quick status update. After another restart on January 17, 2008, I upgraded to the BIOS dated January 16, 2008. Since then, I have not had another CPU fan roar and reboot. However, it has only been one month, so that may not be long enough to know for sure if the January BIOS has fixed the issue permanently.
If you have the time, definitely read all the comments from my previous post as there are some other things you can also try in addition to the BIOS updates (though I have not tried them). There is a good thread about this on the c|net forums as well.
I see there is also another BIOS update from Gateway (dated February 4, 2008), though I have not yet upgraded to that version.