dude~ i hope u already goolgle for more info on ur mobo..this problem is quite common problem meh..my last gigabyte k8nf also shown a wrong value of n/b temperature if i use speedfan indicator..while in the bios, this stupid gigabyte board dont have any monitoring system for n/b temp.. huhu~ i think the temperature is juz a bug, try to mod ur mobo by installing iceberg5 n/b cooling fan~

this kind of mod work will various type of pc