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.

yes. i have updated the bios. no change have been made.

I'm surprised that there are people with similar, if not exact same problems as I do.
Still hoping for a lifeline =/
BIOS always showing temp at 40 degrees Celsius, regardless of idle/cold boot/after playing 2 hours of Crysis.
Speedfan, HWmonitor, CoreTemp all show CPU temperatures at 10-22 degrees Celsius, which is obviously out of any cooling capability of HSF, regardless of my Zerotherm heatsink.
I'm thinking about purchasing an analog sensor to put near the CPU to monitor its temperature. I've overclocked the CPU from 2.7 native to 3.1 running stable. I would like to push it further, but of course, not knowing my current temp is a serious obstacle.

Specs:
MoBo: ECS A780GM-A
CPU: AMD Athlonx2 7750 BE
HSF: ZeroTherm Zen
vCard: nVidia Geforce GTX 260
Case: Raidmax Aztec
RAM: 2x2GB GSkill 800 DDR2

Any help would be much much much much appreciated. Thanks in advance.

If I were to disregard temperature readings (no matter how false they may seem) and only use gaming stability, wouldn't that put my CPU under risk of getting fried during heavy loads? I already consider myself to have a pretty good heatsink, although, without temperature readings, I can't really justify. Also, why would I want to cool my northbridge integrated graphics when I'm using the GTX260?

Thanks for the help.