This only applies to supercooled computers. I thought this would come in helpful, as I've been insructed wrong on how to do this several times. This was taken from: http://www.phase-change.com/phpBB2/viewtopic.php?t=1107
I in no way take any credit for the following information. All credit will go to SLI15 over at the www.phase-change.com
I've been studying CMOS operation and theory and have been researching specifically what happens when CMOS devices are cooled down to 77K(-196C) to 233K(-40C). It's been proven that CMOS devices perform BETTER with lower voltages when super cooled than with higher voltages and higher voltages lead to poorer performance.
They say the best performance when super cooled comes when the current through a CMOS device is just above the threshhold needed for stable and predicted performance. Since resistances and other parameters dealing with current through CMOS devices improve as temp lowers, current through the device will increase, so voltages can be lowered improving performance(At Same Operating Frequency)
When overclocking, a lot of people just crank up the voltage automatically without a cause/reason for it. From what I've researched and other companies have researched and document, Increasing voltage in supercooled CMOS devices to a level where it greatly exceeds the needed threshold voltage, HURTS PERFORMANCE AND LEADS TO DECREASED RELIABILITY.
If your doing 2 volts to your processor supercooled(-40C and below), your only hurting performance if it can operate stably at the same frequency at a lower voltage. Not only does it perform WORSE, but Reliability decreases drastically.
I've noticed in my HSF air cooled setup, I got marginally better PCmark and 3Dmark scores with lowest stable voltages than with all voltages maxed out on a Voltage modded ASUS A7N8X Deluxe with a Barton +2500 OC'd to 2.3GHZ and this is at positive 313K (40C).
WHEN OVERCLOCKING, ONLY BOOST VOLTAGE AS NEEDED, AND IF YOU GAIN NO MORE RESULTS FROM BOOSTING THAT VOLTAGE, GO BACK TO THE LOWEST STABLE VOLTAGE OR ELSE YOUR ONLY HURTING OVERCLOCKING PERFORMANCE AND RELIABILITY.
You heard him. Helped me greatly in my OC quest, and this little tidbit of information will go a long way, I can guarantee you that.