Ryzen: worth upgrading memory from 2400 to 2800 MHz?

[h3r3t1k]

I have a budget pre-built PC with a 2200G and one module of 2400MHz RAM. Now I know you should have fast dual channel memory for the graphics portion but bear with me. I'll add a RX 560 4GB. Now the buddy who has this card also wants to sell me a 2800 MHz kit with the same 8GB total capacity. I wonder if I should buy it as well or if the additional speed plus dual channel doesn't matter anymore with a dGPU... Help!

 

[photonboy]

Actually you should have fast dual-channel for the CPU portion as well with Ryzen CPU's.

Depending on the application you will see gains up to 3200MHz or so (in Dual Channel) so the bare minimum I recommend is another stick of 2400MHz memory in Dual Channel.

It doesn't matter in the slightest when using a graphics card as the GPU accesses its own local pool of video memory on the card and not the DDR4 memory.

Obviously have the monitor hooked to the CARD not the motherboard or you're not using the card.

 

[photonboy]

https://www.anandtech.com/show/12621/memory-scaling-zen-vega-apu-2200g-2400g-ryzen/4

AotS is very CPU intensive so its more like an unrealistic stress test. TOMB RAIDER is closer to typical gaming usage. Note the big jump from 2133MHz to 2400MHz then minimal gains.

Some games like Witcher 3 may get 5% or higher going with 3200MHz vs 2400MHz but the point is it's small gains typically.

Sticking with 2400MHz single channel though is going to be big losses at times since for the sake of the final Rise of the Tomb Raider chart that is "1200MHz" (2400MHz single)… so if 2133MHz is suddenly a big bottleneck 1200MHz would be much worse.

 

[h3r3t1k]

I would be going from 2400MHz single channel to 2800MHz dual channel, not from 2400MHz to 3200MHz. You're saying it's worth it?

 

[photonboy]

I would be going from 2400MHz single channel to 2800MHz dual channel, not from 2400MHz to 3200MHz. You're saying it's worth it?

I realized that.
Worth it? Yes.

Try to understand that last RotT chart in the link I gave. It basically shows 2133MHz Dual Channel causing a CPU bottleneck causing a noticeably lower FPS than at 2400MHz Dual Channel.

Assuming the same timings then 2400MHz SINGLE channel is the same bandwidth to the CPU as 1200MHz Dual Channel. So if I was forced to GUESS you might drop to 70% the performance in some gaming situations.

(actually for that benchmark the 2133MHz Dual Channel is already down to 76% of the maximum it can do with the same hardware but higher DDR4 bandwidth... so 2400MHz SINGLE would be even lower. hard to guess actually. 60%?)

Every game will be different. It will be worse in some and less of an issue in others.