It isn't surprising to see cores boosted to 1.5V using precision boost. Precision boost will determine the thread level of the applications you are running and boost the cores accordingly. Certain motherboard manufacturers implement more aggressive algorithms, that may boost things further depending on the cooling you have.
When you say your CPU can't hit 4.1ghz on all cores, how are you overclocking? P-state, multiplier?
Multiplier. As I said I can play games on 4.2ghz but I can't pass prime95 even on 4.1. I made 4.050Ghz with 1.34V today. Memory is stable in blender 3333 VLL. Another question is how much processor can last if I use scalar x10 for PBO.