Now Asus Probe is saying my MB is at 47C, NB is at 46C and SB is at 49C. Dont know what SB or NB are.
NB, depending on the cpu platform does several things. Ties the video to cpu, runs the memories (Intel) OR simply ties them to cpu (AMD).
SB, does things like the sata and raid built on mobo, USB ports etc.
There are COMBO chips too where NB and SB ar eone called single chip solution. Those WILL run hotter of course and the SB temps will be higher then on a two chip one.