RAM selection for Ryzen APU

[khaled2012]

I know ryzen systems perform better on dual channel memory. And performance of ryzen APU increases with memory speed. But which one has the most impact on performance on a ryzen APU? is it the speed or is it the dual channel configuration?

 

For example, while choosing memory stick for a ryzen 3200g running on a b450 board, which one should i go for.

a) one 16 GB stick of 2933 MHz

b) two 8 GB sticks of 2400 MHz 

 

The PC will be used both for light gaming and light productivity works.

 

Pardon me if this topic has already been discussed and put the link to the existing thread.

[gloop]

Budget for RAM and country?

 

Both are options that I'd avoid.

[Haro]

5 minutes ago, khaled2012 said:

But which one has the most impact on performance on a ryzen APU? is it the speed or is it the dual channel configuration?

Both 

More bandwidth and high speed 

Me personally I would go for the extra bandwidth

[khaled2012]

2 minutes ago, gloop said:

Budget for RAM and country?

 

Both are options that I'd avoid.

In my region, both of the options cost almost the same. FYI, i asked this question looking for a technical insight and to know how differently the "channel" and "frequency" of memory impact a ryzen APU.

[marmour]

8 minutes ago, khaled2012 said:

 

What country? In my region you can get 3200mhz kits for cheaper or the same as most 2400mhz kits

[Haro]

Just now, khaled2012 said:

FYI, i asked this question looking for a technical insight and to know how differently the "channel" and "frequency" of memory impact a ryzen APU

FYI, the advise @gloop said is good 

Both are bad options lol 

Go for an aegis kit for cheap

At like 3000 cl16 

More bandwidth and the frequency is decent

[khaled2012]

3 minutes ago, TofuHaroto said:

Both 

More bandwidth and high speed 

Me personally I would go for the extra bandwidth

But if i had to choose only one of them, which one should it be? And why? I'm looking for a technical insight.

[Haro]

Just now, khaled2012 said:

I'm looking for a technical insight.

What do you mean by that ?

 

Just now, khaled2012 said:

But if i had to choose only one of them, which one should it be?

Out of these kits ? 

Non 

[khaled2012]

3 minutes ago, marmour said:

What country? In my region you can get 3200mhz kits for cheaper or the same as most 2400mhz kits

In my region, both of the options cost almost the same. FYI, i asked this question looking for a technical insight and to know how differently the "channel" and "frequency" of memory impact a ryzen APU.

[porina]

The difficulty here is that it is an older Zen+ APU. You have two conflicting requirements. The Infinity Fabric (and things tied to it) runs at ram speed, so you want that to be fast for best CPU performance. The GPU part needs all the bandwidth it can get. Dual channel 2400 a lot more than single channel 2933. So for gaming assuming you're not using a separate GPU, I'd go dual channel. For other uses, it could swing either way and you'd have to look up specific benchmarks for each use case.

[khaled2012]

3 minutes ago, TofuHaroto said:

What do you mean by that ?

 

Out of these kits ? 

Non 

Bro, you didn't understand my question. I just want to know is it the speed or is it the dual channel configuration that affects ryzen APU performance the most. And I'm looking forward to know why from a technical point of view. 

[Haro]

Just now, khaled2012 said:

that affects ryzen APU

Apu is bandwidth

Interconnect / cpu as a whole is frequency

[khaled2012]

7 minutes ago, porina said:

The difficulty here is that it is an older Zen+ APU. You have two conflicting requirements. The Infinity Fabric (and things tied to it) runs at ram speed, so you want that to be fast for best CPU performance. The GPU part needs all the bandwidth it can get. Dual channel 2400 a lot more than single channel 2933. So for gaming assuming you're not using a separate GPU, I'd go dual channel. For other uses, it could swing either way and you'd have to look up specific benchmarks for each use case.

Thank you for your detailed explanation. One thing you might have missed is that vega 8 gpu of ryzen apu runs faster with high speed memory and delivers better graphics performance. I guess that's less significant for overall gaming performance than double memory bandwidth. And you're correct. We have to look for benchmarks to know the difference. Till now, I haven't found anyone explaining the impact of memory frequency and bandwidth on ryzen APU in a broad technical perspective.

[khaled2012]

25 minutes ago, porina said:

The difficulty here is that it is an older Zen+ APU. You have two conflicting requirements. The Infinity Fabric (and things tied to it) runs at ram speed, so you want that to be fast for best CPU performance. The GPU part needs all the bandwidth it can get. Dual channel 2400 a lot more than single channel 2933. So for gaming assuming you're not using a separate GPU, I'd go dual channel. For other uses, it could swing either way and you'd have to look up specific benchmarks for each use case.

And what if i were using a ryzen 3600 with a separate mid budget graphics card like the gtx 2060? Bandwidth or speed? which one will have the most impact on gaming and productivity?

[Haro]

1 minute ago, khaled2012 said:

Bandwidth or speed?

Speed 

[khaled2012]

2 minutes ago, TofuHaroto said:

Speed 

why?

[porina]

8 minutes ago, khaled2012 said:

Thank you for your detailed explanation. One thing you might have missed is that vega 8 gpu of ryzen apu runs faster with high speed memory and delivers better graphics performance. I guess that's less significant for overall gaming performance than double memory bandwidth. And you're correct. We have to look for benchmarks to know the difference. Till now, I haven't found anyone explaining the impact of memory frequency and bandwidth on ryzen APU in a broad technical perspective.

Generally speaking, games are more likely GPU limited, so leaning the performance there would probably help more. The limitation on APUs is often system ram bandwidth. Thus my suspicion that dual channel slower ram would give better general gaming performance than a single channel higher speed kit. Yes, there are other factors that benefit from faster ram, more so than total bandwidth, but to me this is secondary. The best way to look at these is to run actual benchmarks.

 

I don't have any Ryzen APUs so I've not done that specific testing. I had attempted in the past to see if single channel higher speed for the CPU was better or worse than dual channel at lower speed. That is with a separate GPU so the CPU wouldn't have to compete there. My conclusion at the time was the difference was so small I could not confidently say one was much better than the other. I forget, if it was Zen or Zen+, but not Zen 2.

 

3 minutes ago, khaled2012 said:

And what if i were using a ryzen 3600 with a separate mid budget graphics card like the gtx 2060? Bandwidth or speed? which one will have the most impact on gaming and productivity?

I haven't done it with Zen 2, but for past generations, as described above, there wasn't much in it. With Zen 2 you can at least run IF at higher speed separately from ram, and negate some of that influence. My personal preference would be to go dual channel every time compared to a faster single channel.

[Haro]

Just now, porina said:

IF at higher speed separately from ram, and negate some of that influence. My personal preference would be to go dual channel every time compared to a faster single channel.

I would go the same route 

But afaik with zen 2 speed is more beneficial than bandwidth but I could be wrong 

[porina]

12 minutes ago, TofuHaroto said:

I would go the same route 

But afaik with zen 2 speed is more beneficial than bandwidth but I could be wrong 

The demand for faster ram on Ryzen (all generations) has been driven by the IF being tied to ram speed. This probably remains optimal, given the choice, to get the fastest ram you reasonably can to pair with it. However Zen 2 now allows IF to be set asynchronously from ram. I vaguely recall Linus and others doing testing on this when it came out, and running slow ram but with IF turned up still gave an improvement over just slower ram. IMO Ryzen is very unbalanced when it comes to compute potential and ram bandwidth, even with the caches to help offset that, which is why I'd lean towards bandwidth over speed if I had to make that choice. Ideally, you just get faster ram and have best of both worlds.

[Haro]

Just now, porina said:

Ryzen is very unbalanced when it comes to compute potential and ram bandwidth, even with the caches to help offset that, which is why I'd lean towards bandwidth over speed if I had to make that choice. Ideally, you just get faster ram and have best of both worlds.

I would not change a single thing in this 

Completely agree