Silly max memory speed question

[MoridinUK]

The AMD Ryzen 9 7900X says it will only support 5200 memory max. But it also says it has EXPO features on it to overclock the ram.

So assuming my mainboard says it will run faster memory will putting this kind of 6000 memory in actually be worth while or should I just stick to 5200 memory?

The AMD site says Max memory speed

2x1r 5200
2x2r 5200
4x1r 3600
4x2r 3600

Which suggests it can use ram at 5200 if you use all the memory slots on the mainboard?

 

[tamzzy]

How much ram do you need?

 

[Tetras]

The AMD site says Max memory speed

2x1r 5200
2x2r 5200
4x1r 3600
4x2r 3600

Which suggests it can use ram at 5200 if you use all the memory slots on the mainboard?

No, not if there are 4 slots.

Lemme translate:

2 sticks, 1 rank each (i.e. 16GB or 24GB): 5200
2 sticks, 2 ranks each (i.e. 32GB or 48GB): 5200
4 sticks, 1 rank each: 3600
4 sticks, 2 ranks each: 3600

From what I've heard, you can do pretty well with 4 single rank sticks in some boards, but it is still not a configuration that is recommended.

4 dual rank sticks is a problem and it can achieve just 5000 or less, depending on the CPU, motherboard and memory.

So assuming my mainboard says it will run faster memory will putting this kind of 6000 memory in actually be worth while or should I just stick to 5200 memory?

For content creation the difference tends to be quite small, but it does depend on your specific workload. Puget have a DDR5 article here:

Impact of DDR5 Speed on Content Creation Performance (2023 update)

DDR5 memory has kits rated for up to 8400 Mbps, while desktop CPUs only officially support up to 5600 Mbps. How much does running at official specifications actually impact performance in common content creation applications?

www.pugetsystems.com

For gaming, the difference is more significant, especially with a non-X3D CPU and something best avoided (I mean, running RAM lower than 6000) if possible. HUB did a memory scaling article awhile ago that includes both X3D and non-X3D, though keep in mind that the resolution and graphics card used does change things.