Some people don't understand that a microcode has nothing to do with Mem-OC.
Microcode is used to customize features of a CPU but not to increase mem performance, other settings in the bios are responsible for that.
Mem-OC strongly depends on IMC, mem and settings. If you have the wrong settings, the high clock rate will not work even with the OC bios.
I use 8k CL32 all the time with my old 12900k without any problems, with 14900k you can also use 8400 CL32 for benchmarks without any problems. For 24/7 I would go to CL34 and use a little less voltage.
My settings for voltage are very relaxed, SA 1.23-1.27, VDDQ/VDD2 1.325/1.375 - 1.40/1.45, depending on CPU and the memory clock.