Z790 PG Riptide XMP issue

XMP and EXPO lead to a lot of confusion. Both are technically an overclock, simply
an overclock that the RAM manufacturer has tested and validated on a handful of
systems.
The problem is that this doesn't guarantee that the RAM will be capable of these
speeds on every configuration. I can't count the number of threads here on the forums
where people have come looking for help for this exact reason. Part of the issue
is that BIOS settings and updates can sometimes get things to run at the RAM's
rated XMP settings which leads people to think that it's always the motherboard
that is at fault. In reality, RAM compatibility and frequency support is far more
complicated than that. Frequency support begins with the CPU and the memory controller
built into it. Then there is the architecture of the motherboard's RAM slots and
configuration and only then the BIOS and settings.

When the memory controller used to be located on the motherboard as a separate,
discrete system RAM compatibility and frequency was much simpler.

Issue number two is that most people don't realize how little RAM frequency actually
effects the average user in most cases. The difference between 5600 and 6000 for
example is so small you wouldn't even notice it in some benchmarks. The problem
is that most of us feel that if we paid for a certain speed rating we expect to
be able to achieve it. In reality, it is far less significant and impacting than
the marketing would lead you to believe. Sure, some tasks and use cases will benefit,
including games but with games it only really matters to people chasing FPS to
brag about in a benchmarking capacity.

Now, I say all this to potentially save you a ton of messing around and headaches
trying to get things to run at their rated speed only to be disappointed that it
didn't really make any difference you can notice. If it is still important to
you and/or you are one of the few that actually needs the extra RAM throughput
for your use case then you are going to need to take a deep dive into BIOS settings,
RAM timings/sub timings and tutorials online. Unfortunately I don't have a DDR5
based system so have not really played with overclocking it. Google should have
all you need to adjust timings and voltages etc to get more out of your RAM.

Personally, I don't recommend it, stability and reliability mean a lot more than
1 - 5 FPS in a game that is already running at 60fps+. It won't net you any gains
at all if the GPU is the bottleneck either. Chasing RAM frequency is a game for
overclockers looking to set records or eek every last FPS out of their flagship
tier parts.

I hope this is in some way helpful.