The stock speed voltage is around 1.3-1.35V.
Because those chips are known to be hot running, people like to find the lowest voltage they can run them at and that will lower the running temps.
If you want to try this, the first thing you have to do is download and install the latest bios for the MB. Then download Memtest86+ Link make a bootable CD or USB stick with one of the image files. That program you use before booting into the operating system, let it run for ~10 minutes to make sure the memory is not creating errors. Also download Prime95 Link when you install the program select "just stress testing". When you run the stress tests with that program there will be 4 'workers' running and you just have to keep checking it to make sure non of the workers have stopped (little icon turns red).
So you begin by going into your bios and you lower the voltage to your CPU, then boot to the Memtest disc and run that and make sure there are no errors, then boot into your operating system and run prime95 for 10-15 minutes and make sure its stable. You can also use CoreTemp to monitor you temperatures and whatever progress you will be able to see that in the temperatures getting lower. link
edit: I corrected my previous post and added the word "don't", as in you don't want to leave the case door open.