I could overclock my chip at crazy voltages and do some "temporary screenshot overclocks" if I felt like it. My goal was 3.5 for this chip. That's not my goal. I was looking for the maximum stable frequency I COULD run if I didn't care for the longevity of my CPU.
Serpent has said and my experience has confirmed that normal operation of a PC, regardless of application, will yield 10-15c lower temperatures than heating it up with Orthos/Prime. My goals for overclocking this were to see what would be a reasonable 24/7 speed.
The reason I mention longevity is because overvolting a CPU will eventually lead to instability. For instance, I have a friend that overclocked his E4300 and ran at 3.6GHz with 1.6Vcore on water for about a year. After that time, he started experiencing crashes and general instability. He tried raising Vcore a little bit and just couldn't get it stable, even up to 1.65v I believe. So, he dropped to 3.5GHz and backed back down to 1.6v. It became stable again at the same voltage but a lower overclock. The chip developed a 'tolerance' if you will. Another poster explained this better in another thread, but I like my analogy better.
My point is, I didn't go for temporary overclock screenshots. I wanted to see what I could reasonably run 24/7 if I wanted to. The overclocks I posted are perfectly stable, I just didn't want my chip to be over-volted 24/7 (until I can afford a new one, should it croak).
Anyway...to your question. Someone posted a topic over there about the longevity of the folks in the 4GHz club regarding how long they ran it. Only one person responded and he was running and E6850 at 4GHz (well, 499*8 for 3.99) at 1.58Vcore with a TR Ultra 120 for four months & counting. (
Link)
You could run 4GHz for as long as your chip lets you. No one knows how long the process takes for it to need more voltage to remain stable. Well, I haven't seen it. I'm sure someone knows the properties of the materials and how they relate to the extra current.
To begin with, see what kind of voltage it takes for you to reach 4GHz and remain stable. Then see if your temperatures are reasonable. Then you'll have a decision to make. If it's stable at a low enough voltage that you think you have headroom to move when it decides it needs more current, go for it!
I'm talkative today...don't want to be sitting at this desk, that's for sure.