i have a 2400+ on a shuttle an35n and it sayts unknown CPU but it always will
mine is running 11x200 currently, it will do 11.5x215 and 12x210 for about 2.5GHz and 1.825v, temps are fine
the only way mine is recognized if if its running at 600MHz which it defaults to, dont worry about it its no big deal
try running your ast 11x166, that will give you 1.8GHz whihc is what teh chip is supposed to run at, and it still wont be recognized but that doesnt matter
start at that setting and them move up 11x200 shoudl be dooiable without any increase in voltage