Memory question + adding sticks without pairs

[jak3676]

Is is possible to have dual-channel mode for 2 sticks, but then single-channel mode on the 3rd stick? Or does that make them all run in single-channel mode? Does this vary by motherboard/BIOS manufacturer? I would think your BIOS/UEFI would show the end result.

Having said that, the performance impact of single vs dual-channel mode is generally small - maybe a 1-2% difference in overall game performance for most games. However there are some games that are impacted more than others. In a quick google search, I could not find anyone who has done testing on WoW with the current BFA client. (sources: https://www.cgdirector.com/single-du...-threadripper/, https://techguided.com/single-channe...-quad-channel/, https://www.hardwaretimes.com/dual-c...ce-ryzen-3000/)

RAM is one of those items where you either have enough or you don't - i.e. adding more than you need does not improve performance. So, unless you were hitting full usage on your previous 32GB sticks (but still less than 48GB with the 3rd stick), then I'd just stick to the 32GB until you want to spend the time popping off the CPU cooler to install the 4th stick. But if you're actually using between 32-48GB of RAM, then by all means leave in the 3rd stick.

[MiRai]

Having said that, the performance impact of single vs dual-channel mode is generally small - maybe a 1-2% difference in overall game performance for most games. However there are some games that are impacted more than others. In a quick google search, I could not find anyone who has done testing on WoW with the current BFA client. (sources: https://www.cgdirector.com/single-du...-threadripper/, https://techguided.com/single-channe...-quad-channel/, https://www.hardwaretimes.com/dual-c...ce-ryzen-3000/)

I'll be absolutely honest, I only quickly scanned those articles, but more often than not the tests:

A) Don't mix channels with an odd number of DIMMs (e.g. they're just testing single vs. dual vs. quad in a closed ecosystem)
B) Don't push a lot of RAM (e.g. solo player gaming performance)

With that, the question becomes, when she pushes beyond 32GB, then what happens? While multiboxing, are some of the games utilizing dual-channel and others not? Is that even a thing can happen, or does the machine just force the lowest common denominator across all applications, which would be single-channel? I don't know the answer to those questions, but if I had to guess, I'd say there is definitely going to be a performance hit in that scenario, in one way or another. Now, whether the user can actually feel the difference is going to depend on the user and how keen they are at noticing changes in their system, but until someone actually tests* using mixed channels while utilizing a lot of RAM across several running applications, I'd recommend that people avoid it where possible.

* Actually testing it with benchmarks, not feelings (e.g. the two configurations "feel" the same).