CPU Temperature problem with ECS A780GM-A mainboard

I have newly obtained an AMD Athlon X2 4200+ and an ECS A780GM-A main board. the performance is so good and every thing is OK. but at mainboard's bios , the CPU temperature is fixed at 40 degrees and it never changes. in windows vista AMD Overdrive shows the cpu temperature at 0 but the other programs such as "Core Temp" , "Fan Speed" , "HWMonitor" , shows the temperature of each core at around 20 when it is idle and at around 26 when it does some job. and when i enables C&Q feature at bios , the temperature that is shown with the programs i said , reduces to around 7. what is the problem and how can i fix it? should i consider this as a problem and should i do effort to fix it?
thanks.

Have you tried the latest BIOS?

I have updated the bios. no change have been made.