Ryzen 9 9950X with 4×32GB RAM

[csendesmark]

Hello All

Most likely I will get the Zen5 9950X, which has dual channel memory controller (wish I could afford the 7960X for the sweet 4 channel MC).
My question is:
What are the experiences with 9950X (or 9900X/7950X/7900X) with 4 installed memory modules?
Or should I go with 2×48GB over the 4×32GB?

 

[kapone32]

With all modern CPUs 2 sticks clock higher and can be more stable than using 4 sticks.

 

[A Computer Guy]

Hello All

Most likely I will get the Zen5 9950X, which has dual channel memory controller (wish I could afford the 7960X for the sweet 4 channel MC).
My question is:
What are the experiences with 9950X (or 9900X/7950X/7900X) with 4 installed memory modules?
Or should I go with 2×48GB over the 4×32GB?
View attachment 359549

My gut says go with 2×48GB but my wallet suggests 2x32GB.

 

[Zach_01]

Hello All

Most likely I will get the Zen5 9950X, which has dual channel memory controller (wish I could afford the 7960X for the sweet 4 channel MC).
My question is:
What are the experiences with 9950X (or 9900X/7950X/7900X) with 4 installed memory modules?
Or should I go with 2×48GB over the 4×32GB?
View attachment 359549

Check the "connectivity" of the CPU on the link below

https://www.amd.com/en/products/processors/desktops/ryzen/9000-series/amd-ryzen-9-9950x.html

These are the supported speeds of Zen5
2x1R DDR5-5600 MT/s
2x2R DDR5-5600 MT/s
4x1R DDR5-3600 MT/s
4x2R DDR5-3600 MT/s

...and Zen4
2x1R DDR5-5200 MT/s
2x2R DDR5-5200 MT/s
4x1R DDR5-3600 MT/s
4x2R DDR5-3600 MT/s

Anything above those speeds is not guaranteed by AMD and its considered overclock.
Better go with 2 sticks if you care about speed.
2x 32/48GB = 2x2R

R = Rank. Meaning how the sticks are populated and configured with memory chips.
Older RAM if they have chips on one side its 1R and on both sides its 2R per stick, but now there are chances that a stick can have populated 1 side and be dual ranked (high density 2R chips)

I think all 32/48GB sticks are 2R no matter the sides, but not entirely sure.
If there are 1R, then such high density chips would be very expensive.

So stick with 2 sticks if speed is important.
DDR5 6000MT/s minimum as you have very good chances to make them work at this speed.
If you want to push your luck with higher speed dont go above 6400MT/s.
But its nothing for sure that the CPU memory controller clock (UCLK) will be able to run at 3200MHz
3000MHz is pretty easy.

FCLK = Infinity Fabric Clock (CPU cores <> IO Die interconnect bus)
UCLK = CPU Unified Memory controller Clock (placed on IO Die)
MCLK = DRAM clock

Optimal speeds for 6000MT/s are
FCLK:UCLK:MCLK = 2000+:3000:3000MHz
For 6400MT/s
FCLK:UCLK:MCLK = 2133:3200:3200MHz

Number 1 rule is to keep UCLK:MCLK on equal speeds at all times
Number 2 rule is to keep FCLK as high as possible (2000+ and up to 2200MHz)
All Zen5 should be able to run FCLK 2000~2067MHz and some of them up to 2133~2200MHz (but dont count on it)

Try to find RAM specifically designed for AM5 Ryzen with EXPO profile(s)
Zen5 CPUs love high speed memory + tight(tweaked) timings (and all Ryzen love UCLK:MCLK = 1:1)

6000 CL30 or lower (tweaked)
6400 CL32 or lower (tweaked)

I think G.Skill announced recently some new Trident Z5 Royal 6000MT/s CL28 sticks
I know they have 2x48GB 6400 CL32 1.35V but kits like this are expensive (~350$, In EU maybe 390~440€ depending the exact model)

If you do go with 4 sticks (4x2R) in the end I wouldn't expect anything better than 5200MT/s or even lower.

Questions:

 

[csendesmark]

With all modern CPUs 2 sticks clock higher and can be more stable than using 4 sticks.

I would go with 6800MHz
If 6800 would be stable when it's running with 4 sticks, I would be happy

My gut says go with 2×48GB but my wallet suggests 2x32GB.

I am already using 128GB (4×32) because I need it.
So 96GB would be a step back already, and 64 would not fit my for my use case

@Zach_01
Thank you, this is really good info
I am running my RAMs at 3200MHz so looks like it is already "OC"-d

https://www.amd.com/en/support/downloads/drivers.html/processors/ryzen/ryzen-3000-series/amd-ryzen-9-3950x.html

For the 3950X:
2x1R DDR4-3200
2x2R DDR4-3200
4x1R DDR4-2933
4x2R DDR4-2667
So I then, consider myself lucky

Not sure if I win the silicon lottery next time...
Maybe the 64GB modules come out soon™

 

[SL2]

L1 talks about memory configuration and what to expect, it starts at 11:03, check it out.

 

[Zach_01]

I would go with 6800MHz
If 6800 would be stable when it's running with 4 sticks, I would be happy

I am already using 128GB (4×32) because I need it.
So 96GB would be a step back already, and 64 would not fit my for my use case

@Zach_01
Thank you, this is really good info
I am running my RAMs at 3200MHz so looks like it is already "OC"-d

https://www.amd.com/en/support/downloads/drivers.html/processors/ryzen/ryzen-3000-series/amd-ryzen-9-3950x.html

For the 3950X:
2x1R DDR4-3200
2x2R DDR4-3200
4x1R DDR4-2933
4x2R DDR4-2667
So I then, consider myself lucky
View attachment 359560 View attachment 359577
Not sure if I win the silicon lottery next time...
Maybe the 64GB modules come out soon™

You wont be able to run 6800MT/s with UCLK:MCLK at 1:1 even with 2 sticks
The only way to go above 6400 is to drop UCLK:MCLK at 1:2
And this would look like this
FCLK:UCLK:MCLK = 2000:1700:3400 (or whatever the FLCK could do on the CPU between 2000 and 2200)
Terrible, terrible configuration with great amount of latency between the memory controller and DRAM (1700:3400)

L1 talks about memory configuration and what to expect, it starts at 11:03, check it out.

Exactly^^

You wont be able to go near 6000 with 4sticks let alone above.
Like he says 4 sticks will go below 5000 for DDR5.
Do not compare it to DDR4.

 

[eidairaman1]

Hello All

Most likely I will get the Zen5 9950X, which has dual channel memory controller (wish I could afford the 7960X for the sweet 4 channel MC).
My question is:
What are the experiences with 9950X (or 9900X/7950X/7900X) with 4 installed memory modules?
Or should I go with 2×48GB over the 4×32GB?
View attachment 359549

Go to asrock, asus, gigabyte, msi, and find the latest chipset on motherboards that support that cpu, you should have a detailed list of what speed and densities you can run on the support pages and manuals

 

[csendesmark]

@eidairaman1
I will wait for the X870E
Although I am concerned about the lack of usable PCIe lanes

How come that the X570 give 16× lanes? That bit disappointing in the newer chips.
@Zach_01
Is it better to run it 1:1:1?
What is the greatest speed while the 9000 series can do 1:1:1?

 

[eidairaman1]

@eidairaman1
I will wait for the X870E
Although I am concerned about the lack of usable PCIe lanes
View attachment 359583
How come that the X570 give 16× lanes? That bit disappointing in the newer chips.
@Zach_01
Is it better to run it 1:1:1?
What is the greatest speed while the 9000 series can do 1:1:1?

Please read this

https://www.amd.com/en/products/processors/chipsets/am5.html#chipsets

 

[kapone32]

@eidairaman1
I will wait for the X870E
Although I am concerned about the lack of usable PCIe lanes
View attachment 359583
How come that the X570 give 16× lanes? That bit disappointing in the newer chips.
@Zach_01
Is it better to run it 1:1:1?
What is the greatest speed while the 9000 series can do 1:1:1?

If you worried about PCIe lanes then I would look at X670E. It would seem that the X870E boards are concentrating on USB 4. A prime example of what you would want would be The MSI X670E Carbon or Asus X670E E Strix.

 

[ir_cow]

Zen 4 and Zen 5 Memory limits are the same. Same IO Die.

So 4x dual-rank you want get much higher than 4800-5200.

 

[Zach_01]

@Zach_01
Is it better to run it 1:1:1?
What is the greatest speed while the 9000 series can do 1:1:1?

1:1:1 was an AM4 thing.
On AM5 best is ?:1:1
The question mark is for FCLK. something between 2000~2200MHz and the other 2 between 3000~3200 on 1:1
You cant run on AM5 1:1:1 because everything has to drop to FCLK and that wasn't upgraded much since Zen2/3 (1800MHz)
So even if FCLK can do 2200MHz to run all of them at 2200:2200:2200 is not good (DDR5 4400MT/s)

So if you are lucky you can do 2200:3200:3200 (6400MT/s). Most people run 2000:3000:3000 on 2 sticks of course. Every number you see in this post is for 2 sticks.
If your luck continues you can also buy a higher than 6400MT/s kit with fast timings and run it between 6000~6400 with super tight timings. If its a 6800 probably wont have a profile for 6000~6400 and you will have to dial almost everything.
But nothing is guaranteed. Every CPU/Board/DRAM kit combo have their own "personality" and pretty much its a lottery where all these will run.
The chances are very high tho with 2000:3000:3000 (2 sticks).

 

[csendesmark]

Please read this

https://www.amd.com/en/products/processors/chipsets/am5.html#chipsets

Cool,
Would be useful if AMD could write specs consistent, and not put up conflicting tables.

If you worried about PCIe lanes then I would look at X670E. It would seem that the X870E boards are concentrating on USB 4. A prime example of what you would want would be The MSI X670E Carbon or Asus X670E E Strix.

10GB ethernet and USB4 are both welcome for me
From the X670E boards I could be okay with the ASUS ProArt X670E-CREATOR WIFI, but I will wait and see what the X870E boards can offer.

@Zach_01
Okay, I will look back to this when I get there, because will not remember otherwise