Intel(R) processors have a voltage range on which they can run at remaining at a safe environment; this voltage vary according to the processor’s load, reason why there is a range and not a specific value. Under stock settings, voltage range is 0.2500V - 1.5200V. An over clocking environment is not technically nor warranty supported.
This can be found at the processor datasheets, page 80 under “Voltage and Current Specifications”: http://www.intel.com/content/www/us/en/processors/core/2nd-gen-core-desktop-vol-1-datasheet.html
For further technical information feel free contacting your local support group during business hours: Phone Support