An ASRock engineer on Reddit shared many of the changes AMD has made to the 1.0.0.7b microcode update that significantly increases memory support. One of the biggest is a new setting called DDR5 nitro mode that alters some of the timing parameters inside the memory controller of Ryzen 7000 CPUs to enable higher frequencies. Memory training has also received some significant changes, allowing users to run the initial memory training algorithm for much longer if needed, which can improve the likely hood of a problematic DDR5 memory kit working on an AM5 motherboard.
According to the engineer, the new update will now allow most Ryzen 7000 CPUs to run at 6400MHz comfortably in a 1:1 ratio without failing and allow some motherboards and CPUs to hit 7600-7800MHz depending on silicon lottery when running at a higher ratio. This is a large change from the past, where anything past 6000MHz was unpredictable from a reliability standpoint.
Of course, these changes come from an ASRock engineer specifically, so we can't be sure if some of these changes are board specific or if all these changes come from the AGESA microcode update itself. Regardless, the new update appears to fix a lot of the memory problems AMD's new AM5 platform has been dealing with since the very beginning, as well as improving support for ultra-fast memory kits in the 7000-8000MHz range (whether stock or manually overclocked).
