ASUS Temp Sensor - Location?

[Texun]

Where do ASUS boards read the CPU temps? I recently built an A7V266C with and Athlon 1.3 and noticed the sensor that is usually in the socket was not there, or I couldn't see it. The temps are 52C idle with AS3 and a Volcano 9 and I have not been able to push it beyond 57C after 2 hours with Burn-In Pro. Seems like I read somewhere that it pulls the temps from the cpu but I didn't think that was built in the Athlons. May be a stupid question but I am curious about the difference.

Thanks.