What should you OC your ram to? Set XMP or EOCP or whatever your bios says it is, and call it a day, because overclocking ram is the single hardest thing in a pc to OC and get right/stable and rarely shows any benefits over XMP settings.
While I can give you kudos for actually asking the question before diving into ram OC, the fact that you felt you needed to ask just screams that it's way above whatever knowledge of pc's you do have, and should not be attempted until you get a serious grasp on ramifications of manual timing adjustments.
So just enable XMP.