Be patient with me since english is not my native language.
So far i have been able to lower my voltage from 1.520v to 1.456v stable @ 5.1ghz. how did i do it?
i got my sandy bridge on release day and have been overclocking, trying to find out a stable highest clock with lowest voltage. People might think that it is easy but is not cause is to much time consuming. You are never satisfy with your speed cause you want you reach a new safe limit of it.
after trying so many thing and having a good batch (i know it doesnt matter much) i couldn't understand why everyone was beatting my voltage.
The problem lies in the RAM and VCCIO voltage. Sandy bridge overclocking seems to be afected by ram (size and overclocking) and VCCIO volage somehow. i see that must overclocker can achive higher core/lower voltage with only 4gb (2x2gb) while people with (2x4gb) can also reach it but with higher voltage (core voltage).
i started tweaking with all voltage. i spend 2 entire days doing this, enabling and disabling, prime95 and all. I found out that if you have 8gb and overclocking your ram is limiting to have a stable overclock with lower voltage and you might think is the CPU fault.
After working with all the voltage my motherboard has to offer, i went back to VCCIO voltage (every other voltage on auto) and notice that if i decreased it my overclocking at same VCORE would become instable (0.800v). BUT increasing VCCIO BECAME STABLE AT LOWER VCORE. i was able to decrease my vcore from 1.520v to 1.456v by increasing VCCIO voltage to 1.18V. Do not go overboard on VCCIO voltage and try to maintain 1.2v or lower.
Before my pc would not boot 5.1ghz with 1.48V and now i'm prime95 4 hours stable with 1.456v. I even think that i can go even lower.
Please do not bash my post just trying to help because that is why we are here right...
Nice post. I've been struggling with my 24/7 4.8GHz OC as of late. I've found better stability by *lowering* my VCCIO below standard in BIOS. I've tried all the BIOS revisions from Biostar, and finally noticed that Biostar's BIOS overvolts VCCIO slightly. For example, when I set it to 1.05 in BIOS, that reads 1.104 under load (per Toverclocker). When I set it to 1.025 I get 1.068 - 1.080 under load. Since then, I have gotten the machine very close to stable.
As far as increasing VCCIO to replace VCORE, the way I understand it it's really all the same, since the VCCIO is for the IMC, which is on the chip anyway. Makes sense more VCCIO needs less VCORE, but in my testing, adding VCCIO added way more heat and no stability. The consensus seems to be that high VCCIO is only needed for running really high memory frequencies.
I don't have the answer, your method may in fact work on your board. It just seems to me that this method is robbing peter to pay paul.
I tried 1.025v vccio to counter the overvoltage and it was stable gaming for a day or so, I put it (VCCIO) back up to stock cause I was paranoid of idle BSOD's but it never happened. If I BSOD I will try lowering it again. Yea I was having some stability issues at 1.43v 5ghz I bumped it up to 1.44 and it seems good. The problem was that it passed every stress test including 8 hour blend but when gaming it only drew like 1.42v instead of 1.43v so I overvolted to counter this.