Might or might not need to disable the power saving setting in CPU page too /certainly if you go higher (it is the 2 at the bottom -look at side description "reduce power /power energy save state" )I cannot remember the names ATM). Though I would guess you could obtain 4.0-4.2 with 1.35V (could go 1.4V- on mine I did not use 1.4V /1.85Vpll until 4.55ghz) However, each time I used max memory speed in xmp setting so I had to bump dram/qpi (CPU VTT) V some like 1.2 to 1.4V.

Sometime Asus auto settings can really over do it. Like Auto when I using 32gb at 47x100. Auto runs my VCSSA at 1.38V, I have LinX down to 1.15V (I started at 1.25V)- Been solid on 109runs of Linx, so that was like 2 days. I turned the AC (it was 60F out) to keep the room cooooooool. Even with 3 RADs I dont want to have to stress cpu anymore than I have to while doing math:p