I believe him. Speedfan also gives simular readings for my computer too
I'm running a Phenom II 920 overclocked to 3.6ghz on an ASUS M3A78-EM.
When i run 3dmark06, this extra "Core" reading in speed fan reaches about 73C. I have NO idea what this sensor is referring to, but the first "Core" maxes out at 45C which is agreeing with the ASUS motherboard monitoring software.
No other temperature matches with this other reading on the ASUS mobo software, which really throws me for a loop. Whatever it is, it's getting really hot..