Unlocked 550BE overclocked to 3.6Ghz what temperature should I risk

Yesterday I built a PC with a Asrock 880G Extreme 3 motherboard a AMD Phenom II 550 black edition and a coolmaster hyper TX3 cooler and immediately unlocked 2 extra cores in the motherboard settings. Today I tried overclocking to 3.8GHz which looked stable but the temperature started to reach 60C so I went back to 3.6GHz which ran fine with 1.45V @ 44C when running the stability test in the AMD overdrive utility but when I ran Prime95 the temp. went to 59C I dropped the voltage in increments back to 1.4 (1.875 is not stable) and the highest temp when running Prime95 is now 53C max is this OK for regular use? If not what temp should I be aiming for?
 
53C in Prime95 is fine (figure it is maxing out all 4 cores which will very seldomly if ever be done in actual usage) and 53C is still quite a ways from the 70C max temp of the 550BE.

 

Thanks for the info, since I started this post 3.6GHz crashed after around 1.5 hours of prime 95 so I dropped to 3.5GHz @ 1.3875V and it seems to run Prime95 indefinitely and temp never goes over 49C.