Some systems are less stable with 4 dimms populated instead of 2. This is the only real valid one I can think of.

Or if you have an algorithm that tries to use all available ram, it will spend more time filling up more ram. Though that's the stupid algorithm, not the RAM.

Or if you add virtual ram and run programs to the point where it needs to constantly page data out and in. Though that's running more programs than you have ram for and it suffers from a lack of RAM, not the other way around.

Maybe with bad RAM refresh settings where all RAM access is paused during refresh will slow down the system with a sufficient amount of RAM if it needs to be refreshed in series. Though I'm pretty sure I've already seen UEFI settings to do that dynamically over sections of RAM, plus I think that RAM already parallelizes it inside the dimms because it's an obvious limitation for them.

Oh, another real one, though I don't think it has a huge impact, but the amount of available RAM can affect how many bits are used in the data structures used to manage/track memory allocations, and the number of bits could determine the size of the structures, though those could also be dynamic and depend on memory used rather than available, but I'm not familiar enough with memory allocators to say for sure (both whether it would be a factor at all and how well current managers would handle it). Though even if it does make an impact, each bit added means double the RAM handled, so it doesn't even scale that badly, and could be optimized to that "used" version if it is the "available" version.

So yeah, without a better mechanism to create bottlenecks, I'd call BS on that statement.

Have more ram then the cpu can address

What worse bottleneck then not being able to boot?

(If anyone has this problem i will gladly take the ram)

I guess bigger ram might have slower speeds and vice versa