First off keep it stable and within manufacturer voltage and temp range if you want it to last awhile which you probably already know.
Than from there are a few different schools of thought. Some people push their CPU's to the max. Others like myself will push their CPU as far as possible while trying to keep the voltage as low as possible which is why my e2180 is at 3ghz with voltage at something like 1.1-1.2v in order to get 3.1ghz i had to push it to 1.4v. Others will try to find a happy middle ground.
But in general voltage and heat kill CPU's, if you want to use it for a long time (to the point where it's considered a historic artifact) the generally accepted thought is to keep those low. And as I mentioned in another post today, the core 2 quads have been around since jan 2007 so close to 5 years and most of those are still chugging along with some good overclocks. And I have yet to hear about one biting the dust.
Actually he can hurt it if he puts way too much voltage, just don't go too far past that recomended limit to keep it safe in my opinion. But chances are by the time he gets there i imagine he won't have as much leeway because once you start putting more voltage in there it creates more heat just from that. So he will have quite a bit more heat to dissipate by than.
Alright thanks for the feedback guys. I've tried o.c. to 3.9 and temps stayed well below 35c on only air, doesn't make sense what eves. But when I was surfing the internet all of a sudden the pc shutdown and a small message said failed o.c. . I'm not sure if it was unstable because I ran prime95 max for like 6 hrs with no errors. Is there something wrong or do I need to up the voltage or just retry the oc. thnx. Btw whats the best o.c. to use from 3.3?
I want something that will give me a bit more performance while still keeping the cpu in healthy conditions to extend its lifetime
IMO i think 62c is recommended for phenom II's, tru upping your voltage by around .0025 and then run intel burn test 20 runs at the highest setting or LinX 0.64, these programs are much more stressful than prime 95 and will generate more heat. Also check your Northbridge and ram voltages if you have adjusted your fsb settings in addition to multiplier overclocking. POst back some results!! all the best