This link is really old but valid to answer your question about the Max Operating Temp for the Athlon II CPUs : AMD CPU's MAX TEMPS! - Overclock.net - An Overclocking Community
Copied from above linked thread:
Today i have decide to make a thread with all amd cpu's max temps...
and there are they:
these are "CORE TEMPS" remember... you can check this link before read maximum temperatures for each AMD CPU (Thanks to ALUCARDVPR) -> http://www.overclock.net/t/1128821/amd-temp-information-and-guide
All Athlon II x2's max temps are -> 74~75'C
Athlon II x3 Series -> 73'C
Athlon II x4 Series -> 71'C
Phenom II x2 5XX Series -> 70'C
Phenom II x3 7XX Series -> 73'C
Phenom II x4 8XX Series -> 71'C
Phenom II x4 9 Series 95W -> 71'C
Phenom II x4 9 Series 125/140W -> 62'C
Phenom II x6 1035T/1045T(new released)/1055T 95W -> 71'C
Phenom II x6 1055T (125W) 1065T 1075T 1090T 1100T -> 62'C
FX8120/FX8150 (BULLDOZERS) -> 61'C
FX6100/FX4100 -> 70'C
Stay Focused with this temps....