Interesting, thanks for the information again.
Opening CPUID monitor it says the CPU VCore voltage, which I believe is what I am after is saying around 1.3 V. Min 1V, max 1.344V. From a quick google, 1.3V I think is considered fairly tame? Whether 1.3V at 4.3 GHz is considered good, I am not sure. Temperatures are fine under load, get to about 72 at max in GTA V, which is very CPU intensive. Sits about 45 degrees C average when browsing etc, tad high but not dangerous.
It seems then you are saying that with proper optimisation, I can probably get more bang for the buck, probably get a higher clock speed, and keep roughly the same temperature profile, if I messed around a bit with everything.
edit: So I went in to the BIOS. The CPU voltage in there says 1.1V, not 1.3V as CPUID monitor says. In advanced menu it says something like 'all cores attempt to boost to 4333mhz'. So maybe in this mode, it just extends the boost up to 4.3, where as stock wasn't it like 3.7? So potentially my CPU might only go up to 4.3 under heavy load. And sitting here now, maybe it is only 3.3?
The BIOS monitor will show the voltage at the base multiplier for the processor, which is either 33 or 34. You might want to look at it with EIST enabled and then disabled (with the required reboots to BIOS), to see if EIST has any affect on the reported value. My vague recollection is that it doesn't. I could look at my notes from four years ago -- because I still have them.
I'm speculating somewhat, but I'd think the 1.3V reflects the auto-overclocking's excessive voltage with EIST turned off in BIOS. And I'd begin your sojourn of overclocking with both EIST and C1E turned on -- all the default energy-saving features. With EIST enabled, Windows monitoring and CPUID CPU_Z would report an idle value between 0.9 and 1.1V.
So, yes, I'll reply to say that you should be able to have the processor "turbo" on all cores to a nominal 4.5 Ghz to show a peak voltage close to what you already see.
You should read some overclocking guides from online resources, and not just one of them, for OC'ing both Sandy Bridge and Ivy-Bridge processors on the Z77 chipset -- preferably using the ASUS P8Z68 and P8Z77 models and their BIOS'es as reference.
As I said, take inventory and keep a notebook. I don't have the Z77 BIOS at my fingertips, and you should look through the menus to find an item resembling "Extra voltage for turbo mode," in addition to the Offset and other voltage settings in the tuning or "tweaker" menu. If you do find this second voltage setting, it can be used with the Offset voltage for settings that keep the actual VCORE from exceeding VID. If you don't have it and can't find it, it would mean that the Offset voltage would be your sole means of voltage adjustment.
Load-line Calibration -- LLC -- will decrease the default "droop" built in to the circuitry which keeps the same thing from happening under heavy load. You may eventually want to tune LLC so it shows a droop of ~2mV under load conditions. The default droop is somewhere in the neighborhood of 6mV to 8mV.
So for instance, you barely stress the processor so all cores still show maximum turbo speed, the peak turbo voltage will register in a monitoring program. When you severely stress the processor, the voltage will be so many mV below that value -- the "vDroop."
But read the over-clocking guides enough so that you can turn off any auto-overclocking, set everything back to default, and begin raising the turbo-multiplier above its default ~36 or 37 a notch at a time, to find the point where "auto" default voltage is becoming insufficient to maintain stability. That would be your first step.
You also have the prerogative to simply use the auto-overclocking for the stable 4.3Ghz and leave it alone, but it WILL be unnecessarily volted, and you CAN achieve higher clocks at similar voltages while keeping temperatures manageable.