Easiest way - take screen shots of your BIOS settings at default, then there is an option in the BIOS CPU level UP, select 4.2 and let it do it's thing, it will set the rig up to 4.2 for you, check for stability, if good can generally lower the vCore and possibly other voltages also - extremely easy (of and get screenshots of the settings after it sets things to 4.2 - that will let you see what it changed - there are also auto tuning options for 4.4 and 4.6, it actually works pretty well, better than the options in the Z87 Hero (I've got both)