Asus ROG STRIX Z690-E GAMING WIFI
Also depends on the CPU's memory controller.
My current i9-12900K can't handle 6400 CL40. It's only stable at 6200 with basic tweaking. Hopefully 13900K or 13900KS can do better.
From the limited benchmarks I could find, it looks like 6600 is faster.
You can't really test RAM by itself in gaming tests. You have to test it with a CPU. And until someone does a memory scaling test with Intel's 13th gen, we'll never know which one performs good enough to get a more expensive kit.