cpu temp help stop

i have recently started to raise my CPU FSB(Athlon 1800) so i want check my cpu and motherboard temperatures(asus A7N8X-X).I have installed MBM 5 and everest and they both show that cpu is at 32c and motherb at 24 most of the time.but on the bios menu(updated) cpu is 45-46 and motherb at 25-26.some people say that when the bios setup is running cpu is idle why is there such a big difference?which shows the right temps?