X870E Nova Wifi 00/03 issue

No one from any manufacturer will answer that question (not AMD, not ASRock, not
ASUS, not MSI etc). Fortunately I don't speak for ASRock or AMD so I can give you
my opinion having watched the AM5 situation from the beginning. If no manufacturer
is answering the question to anyone's satisfaction it's almost always the vendor
that is the cause. In this case that vendor is AMD. The "issue" is nothing more
than a slightly higher failure rate on 9000 series CPUs than has historically been
considered normal. To be perfectly honest, I am not surprised at all. We are really
pushing up against the limits of what is possible with current architectures.
As a result, die complexity, fabrication node size and frequency goals make failed
CPUs far more likely, particularly but not restricted to early batches.

The reason ASRock did not request that you RMA your board is because the board
isn't the issue. Yes, initially ASRock had more failures on their boards than
other brands but that was not due to a quality issue or defect. They had optimized
their boards to extract maximum performance from the 7000 series and some of those
optimizations were problematic with the 9000 series. It took a few rounds of BIOS
updates to locate and address the issue. Things were not helped by the fact that
so many people started to point fingers at ASRock and insist that ASRock had a
major issue with AM5 and the 9000 series. Every possible failure (regardless of
relevancy) was posted on redit by the angry mob. Having watched the r/ASRock
redit from the beginning I saw this trend for myself. User error, people refusing
to admit that they had not updated their BIOS before failure because they didn't
want to be called stupid (I can understand this, redit can be brutal) etc.
At this point failures have more or less normalized across all brands. The 9000
series does not last as long as previous generations because it is pushed much
harder than the 7000 series was on almost the same architecture.

To cut a very long and somewhat speculative story short, AMD has been very good
with accepting RMA requests. I would go ahead and RMA your marginal CPU while
it is still possible to do so. The fact that the "LN2 mode" "fixes" the issue
means your IMC (integrated memory controller) on your CPU is defective, it probably
was from the factory and has only worsened since starting to use it. CPU failures
are not new, they happen with every generation with increasing frequency as CPUs
get more advanced/complicated. RMA exists for this exact reason. Failure rates
are still officially within standard limits last I checked. Around 2.5% which
is on par with intel's latest offerings. 2.5% of millions of CPUs is still a lot
of failures however. That said, the odds are very low that you would receive
a bad replacement CPU. Most often the CPUs sent out from RMA requests have been
better tested than the ones found on store shelves.

I hope this answers your questions and helps ease your mind somewhat.

Good luck with the RMA