Increasing the CPU voltage increases the temperatures of both the CPU and the components on the motherboard that provide power to the CPU. Even if you have adequate CPU cooling then increased voltage will mean more strain on the power regulation components on the motherboard. My CPU for example, can handle a lot more than 3.2ghz (Q6600s are known for lasting for years at 1.5v, 3.6ghz), but I'm afraid the motherboard won't be able to handle it. Increased voltage will also increase detrimental effects on the CPU such as electromigration, this still occurs at low temperatures but as far as I know high temperatures make it worse. I really don't know if there's a specific voltage that if exceeded will kill your CPU instantly or very quickly, but I do know that increased voltage will make the CPU age faster. It might be possible that there is such a point though, since I know some 2nd generation Core 2 based chips would die quickly if the voltage was even a little bit outside of a range. I don't know much about AMDs 45nm SOI process so I cannot give you anything specific to your chip.

http://www.youtube.com/watch?v=OnbBSiXyFHw&feature=related

As far as I know, 4.11ghz is impressive for a Phenom II 965 and you are unlikely to get much more out of it since, as far as I know, going further would need a lot more voltage for little gain. Also I would steer clear of using features that increase the voltage under load or things like Load-Line-Calibration (LLC) unless you know exactly what they do because there has been some concerns about voltage spikes using such features: http://www.anandtech.com/show/2404/5 (the link is for an intel processor but as far as I know AMDs are pretty much the same for the purposes of the discussion).

Of course, you could go overclock as far as you can just for the lols and then replace it with a new AMD 8 core (when those are released later this year) or Core i7 2600K  if you kill it.

If you want a better answer then you're best off asking someone who either has an Electronic Background ( like me in a couple of years ), or asking someone who is intimately familiar with overclocking Phenom IIs.

So as it sits, I remember how hard a time I had pushing the thing to where it is now. Mainly, the difficulty lies with me telling the MB to go ahead and give the CPU 1.65V, and with a 50mV load line calibration, gets it to 1.7V.

Here's the problem with me. The temps hover at 53 max. It takes AIDA64 and super pi @ 8million digits to get that temp. Otherwise, it goes to 51 -52, and stays there.

Even if that isn't the only concern, dagnabbit, I can't help but think it can do more!!!

But I digress. I think that this is the limit for this hardware. I moved the fans from the uncontrolled 4 prong connector to the MB chassis and optional fan sockets for better fan control. Asus had a great utility for Q-fan control that allows for higher fan speed @ higher temps. Try as I might, the MB temp ONLY goes down when under load (at least for where the sensor is...)

I'm callling it phase 2. So far at 4.16, and V@ 1.65. Getting a little scary...
Once I had it to 4.2, but the volts were way out of control, and it wouldn't bench. So, I'll keep trying other things, and see what I get. Wish me luck.