1.4 is considered the safe limit for Ivy Bridge, and is still a good rule of thumb with Intel, though it has edged down a little and typically 1.35 is considered max for daily use.
For everyone's benefit:
Each Microarchitecture, which is expressed in "nanometers" (nm), has a “Maximum Recommended Vcore”. For example, it’s important to point out that 22 nanometer 3rd and 4th Generation processors will
not tolerate the higher Core voltages of other Microarchitectures.
Here's the Maximum Recommended Vcore per Microarchitecture from 14 to 65 nanometers since 2006:
We know that over time, excessive voltage and heat damages electronics, so when using manual Vcore settings in BIOS, excessive Core voltage and Core temperature can cause accelerated "
Electromigration". Processors have multiple layers of hundreds of millions of microscopic
nanometer scale components. Electromigration erodes fragile circuit pathways and transistor junctions which results in the
degradation of overclock stability, and thus performance.
Although your initial overclock may be stable, degradation doesn't appear until later, when increasingly frequent blue-screen crashes indicate a progressive loss of stability. The more excessive the levels of voltage and heat and the longer they're sustained determines how long until transistor degradation destabilizes your overclock. Decreasing overclock and Vcore may temporarily restore stability and slow the rate of degradation.
Extreme overvolting can cause degradation in minutes, but a sensible overclock remains stable for years.
Each Microarchitecture also has a "
Degradation Curve". As a rule, CPUs are more susceptible to electromigration and degradation with each Die-shrink. However, the exception to the rule is 14 nanometer (nm) Microarchitecture, where advances in
FinFET transistor technology have improved voltage tolerance.
Here's how the Degradation Curves correspond to Maximum Recommended Vcore for 22 nanometer 3rd and 4th Generation, which differs from 14 nanometer 5th through 10th Generation:
Degradation Curves are relative to the term “
Vt (Voltage threshold) Shift” which is expressed in millivolts (mv). Users can not monitor Vt Shift. With respect to overclocking and overvolting, Vt Shift basically represents the potential for
permanent loss of normal transistor performance. Excessively high Core voltage drives excessively high Power consumption and Core temperatures, all of which contribute to gradual Vt Shift over time. Core voltages that impose high Vt Shift values are
not recommended.
To achieve the highest overclock, keep in mind that for your final 100 MHz increase, a corresponding increase in Core voltage of about 50 millivolts (0.050) is needed to maintain stability. If 70 millivolts (0.070) or more is needed for the next stable 100 MHz increase, it means you're attempting to overclock your processor beyond its capability. All processors reach a limit where an additional increase in Core voltage will
not stabilize another 100 MHz increase in Frequency.
Here's an example of a Core Voltage / Frequency Curve:
With high-end cooling you might reach your Maximum Recommended Vcore limit before you reach the ideal Core temperature limit at
80°C. With low-end cooling you’ll reach
80°C before your Vcore limit. Regardless, whichever overclocking limit you reach first is where you should stop.
Remember to keep overclocking in perspective. For example, the difference between 4.5 and 4.6 GHz is less than 2.3%, which has no noticeable impact on overall system performance. It simply isn’t worth pushing your processor beyond recommended Core voltage and Core temperature limits just to squeeze out another 100 MHz.
• CPU Overclocking Guide and Tutorial for Beginners
Intel Extreme Tuning Utility
Intel Performance Maximizer
Ivy-Bridge doesn't contain AVX instruction sets, so you'll not need to worry about that aspect.
For everyone's benefit:
Advanced Vector Extension (AVX) Instruction Sets were introduced with Core i 2nd Generation, then AVX2 with 4th Generation and AVX-512 with later Generations of certain High End Desktop (HEDT) X-Series, Extreme, i9s and i7s. Each AVX Instruction Set is progressively faster in calculation workloads,
if you run software that uses AVX codes. Unfortunately, AVX can
adversely affect stability by
overloading your CPU, which will
dramatically increase Power consumption and Core temperatures.
2nd Generation Sandy Bridge processors and 3rd Generation Ivy Bridge processors both have the original AVX Instruction Set, but not the later AVX2 Instruction Set. This is in the Product Specifications website as well as in the Datasheets.
kappsta87,
Here's the nominal operating range for Core temperature:
Core temperatures above 85°C are not recommended.
Core temperatures below 80°C are ideal.
For testing thermal performance, run Prime95 Small FFTs, but to conform with Intel's Datasheets, be certain to disable AVX for valid results.
CT 
Facebook
Twitter
Instagram