Ryzen, and Memory Channels...

[DigitalPanhandler]

so a thread poped up over on steam discussion forums, someones having a issue with their new ryzen 2700x and pubg.... user is running 24gb ddr4 3200, (ultimately his issue was fps is around 30 with a 1080ti)

anywho, in the process of helping diagnose it, some people, I would like to just refer to them as "the less informed know it alls"

we got on the subject of his memory makeup...

I basicly said, well "if user is running 3x 8gb sticks, that could be the issue as 2 are running in dual channel, and the third is running in single channel"

in comes the know it all less informed

"Ryzen actually has a dual memory controller so you can have 3 sticks in and two will run dual and 1 single."

basicly reiterating what I said...... but then trying to refute that it would be a performance bottleneck... (ok how much that may be...not sure, negligible maybe?)

my final response...

"yes but your forgetting one important part, 1. almost all cpus in the past 5-10 years have that, and 2. The problem lies with when the system needs to move something out of the 2 sticks in dual channel, and over to the one stick in single channel, or vise versa, from the one stick in single channel, and into the 2 in dual channel...

the cpu cannot take a single stick and make it dual channel, thats a product of the fact that it takes 2 sticks, to run in dual channel..."

can someone provide more indepth information on this, am I wrong or has something changed along those lines that I'm not aware of?

I don't want to be passing out wrong information, so help would be appreciated....

eh heres the thread in question: https://steamcommunity.com/app/578080/discussions/1/3211505894141629927/

 

[pendragon1]

sounds possible. tell him to take out one stick and see how it acts. who the fuck runs 24Gb in non triple channel anyways?

 

[DigitalPanhandler]

sounds possible. tell him to take out one stick and see how it acts. who the fuck runs 24Gb in non triple channel anyways?

eh who knows, and quite frankly not sure what his overall setup is, he hasn't replied back yet, to many people came in spewing fud, such as "its the cpu, it sucks for pubg" and "its the 1080ti, its being hampered by the cpu"

I don't even know why I bother trying to help people on the steam forums anymore, it always devolves into someone saying "its your mouse...." or some other equally irrelevant information

 

[Aenra]

You've got the gist of it.
It cannot do a proper interleaving as it's only dual channel capable, resulting in the third stick being classified as 'channel'.
Now the performance hit can be anywhere from minimal to significant, application and paging system depending.

Ideally speaking, should one not have a dire need for 24gigs, it would be preferable to stick with 16 in a 2x8gigs configuration, which is also the optimal in our case. But to say that the extra RAM itself is the cause, nuh, no way.
If there's an issue here, chances are it's a BIOS setting(s), unless the user heard some "expert" and has disabled Windows paging.