You need to do a little research first, it's not something that can really be answered in one line. But you want to try to set as many of your auto voltage settings to their recommended standard. So you have a base to work from. Disable turbo core, as you are likely going to be overclocking above this initially. Lots of people will suggest disabling cool n' quiet and application power management (APM) but I personally leave these on. Unless you are overclocking just to get big numbers it's not worth pushing it to the absolute max. Personally when tweaking GX systems I aim to overclock to about 200mhz above turbo speed but across all cores with a voltage decrease rather than increase. 9 times out of ten you can achieve this and it will run faster, quieter and more economical than standard.
Also with a 970 chipset and a 125w chip I would definitely be concentrating on undervolting because that sucker is going to toast up those VRM's.