Why not just use the ''clasic'' diode from PECI ?...

Mine results with an 6400 at 3600@ 1.417v watercooled 24C room 26-27C Radiators(3x dual nexXxos) are...

idle core temp 39-41c (ok i will tell the max of one core only)
idle PECI from AI SUITE 32-33

Full load orthos after 30s
Full core temp : 65c
Full PECI AI SUITE 55C

After some tests i realize that core temp was WRONG.It says 10C More under load and 7-8C on idle.

In my opinion if all previous posts are right them...coretemp is just for some cores/cpus.