Memory I/O Bandwidth on Threadripper Pro

Has anyone verified that 4 sticks dual rank dimms gives 8 channel i/o memory bandwidth on Asus Pro WRX80E-Sage SE Wifi with Threadripper Pro 3955WX?

Or as a general rule x sticks of dual rank yields the same memory i/o bandwidth as 2x sticks of single rank or, in theory, x/2 sticks of quad rank etc?

I’m speccing out a new system and learning a bit about ram along the way.


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Should if you change to Channel interleaving in the BIOS.

Thank you.

Are there any drawback to channel intervleaving? I mean, if there was no plan to increase the amount of memory in the future then would it be better to populate all 8 dimm slots?

if you populate all 8 slots you will be limited to 3200mt/s but to be honest at cas 16 or less. you would have to spend way more money to get nominal performance gains.
should you go 2x4 sticks. meaning 2 separate 4 stick packs?
ideally you want 1x8 pack.
the 2x4 pack may not be stable if bought at different times as components change on ram sticks every week it seems.
so getting 2x4 is always gonna be a bit of a gamble…

good news though…
if it doesnt work you can send it back :slight_smile:
if you can afford it go with the 8 sticks.

as for dual rank i think you mean dual sided dimm v single sided dimm?
as dual rank the rams the slot configuration.
4 alternate slots is single rank.
8 slots divided into 2 ranks of 4 sticks is dual rank.
dual rank gives more bandwidth but at the cost of reduced speeds.
in that you cant run dual rank overclocked ram (>3200mt/s) and have to stick to natively supported speeds of 3200 or under.

dual sided vs single sided dims and interleaving…
if you have dual sided dims enable it.
if you have single sided dims disable it.

it may be enabled by default so check to make sure as it can degrade performance if enabled on a single sided dim.(and likely cause crashing)
it can also reduce performance if disabled and you have dual sided dims.

so it really is just down to which you choose. if configured correctly you should have maximum bandwidth and speeds regardless of your choice…
ps it seems ryzen prefer ( at least at launch) single sided dims.

Same here running the WRX80 Sage 8 channel 3200 but only 64gb. did a bios update now I can run it at 3200 instead of 2100 it was putting it at for some reason.

I would have to re run some benchmarks ( passmark ) with some sticks missing, but I can say this.
I ran for a couple of weeks with 6 sticks ( 16gb 3200 ecc ) and ran some benchmarks ( the usual assortment of Heaven, 3d mark, cinebench, geek bench Puget bench ( Da Vinci ) and then ran them again with 8 sticks.
All of the memory related benchmarks ran with higher scores with 8, and the overall scores jumped too. I was very pleased. No explicit bios changes.

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