Re: cache lets see it then...
A77 cores are supposed to use a similar amount of power to A76s i.e. 5W at 3GHz.
If you compare that to a 3700X on a similar 7nm process (although likely to be low power vs high performance) where you get 8 x SMT cores @3.6GHz using 65W including a lot of cache and IO. I’m not going to try and make an apples vs oranges comparison, just point out they’re in the same ball park.
However, clock everything down to ~2GHz and ARM will win the power race comfortably.