you mean the load line caliberation? Yes its completely safe to crank it up all the way, but I don't see the point if you're just using stock processor. It'll waste more power. That function is so you can OC your processor and attain safe v.
As for XMP, theres a whole explanation on that, not necessarily a manual OC, but yes, you can crank up the voltage for that too. But really, all you have to do is set your power options to high performance in windows and viola, you got a processor running 100 percent without having to mess with the bios and risking screwing up.