Ok, done it.  Not need to remove power supply unit, just swing it out of the way - no idea why the manual states that.

Think it states that just for safety of frying components or zapping yourself (very low chance).

What did you replace your cpu with?

swapped out intel i5 8400 to intel i5 8600k; couldn't justify spending the cash to go to i7.

that's a while back; prices have dropped since then; about 2 months ago I upgraded yet again with intel i7 8086 k which is the top dog for the motherboard.

I need to do this too, I think I'm going to spend the extra and just get the i7 though, then it will be capped. 

I thought about the same thing but the price is still ridiculously high $500+ and there is really minimal difference in performance. Hopefully ya got a good deal on it.

I personally don't understand why the 8086K sold listings in new are so high.  I mean, if it were the highest chip for the 300 series chipsets maybe I could understand more, but 9th gen will also run on z370 if you have the bios update, which virtually all retail boards provide.