You should be able to get to 4.2GHz (enough for even demanding games such as SMG, SMG2, The Last Story etc) very easily, assuming you buy a decent aftermarket cooler.
Also, you won't be able to 'max out everything Wii has to offer' as no hardware in production can run a game at 5xIR with 9xSSAA, but no-one will need that kind of graphics quality. A 560 Ti should get you to 4x IR with 0-4x SSAA, or 3x IR with 4x (or maybe 9x with some games) SSAA, which is very decent.
Also, you won't be able to 'max out everything Wii has to offer' as no hardware in production can run a game at 5xIR with 9xSSAA, but no-one will need that kind of graphics quality. A 560 Ti should get you to 4x IR with 0-4x SSAA, or 3x IR with 4x (or maybe 9x with some games) SSAA, which is very decent.
OS: Windows 10 64 bit Professional
CPU: AMD Ryzen 5900X
RAM: 16GB
GPU: Radeon Vega 56
CPU: AMD Ryzen 5900X
RAM: 16GB
GPU: Radeon Vega 56