Totally normal to have one core 7-10c hotter its just how they are laid out on die.This is interesting while I was checking on alternatives to the pea size drop method for the thermal paste with respect to 212 LED I came across this review https://www.bit-tech.net/hardware/cooling/2017/01/11/cooler-master-hyper-212-led-review/2 for the 212 LED. Notice how far this 212 is from the 212X specially in the socket 2011 even an i32 beats it, I have no idea why most of the reviews which I read gave the 212 LED high marks and if memory serves me correctly in most places 212 LED was shown equal to a 212X or very close.
Anyway here is the latest result from using 2 new intake fans in the front and with existing 1 exhaust fan and 1 side panel fan. I also reapplied the thermal paste "Using a vertical line method" after using a special clearer on both the CPU and the heatsink to remove all oil.
Confirming yes it does make a difference Core1 is closer to Core0 but Core4 went crazier by 7C. My CPU is not HSF off I am frankly scared of it ever since the time of the ivy bridges.
First, in bios make sure you have Asus enhancement disabled , right under AI OC tweaker, as that sets all core to max.
I can't tell from pic what your final Vcore is but at around 4.4 I bet you could be ok with 1.165-1.180v and if you decrease to 4.1 you really shouldn't need much, like 1.125-1.140v.
On that HS base you will need to add paste to between the pipes as those spaces need to be "prefilled" or normal application of paste would not spread it there and you will have air pockets.