Author Topic: Why render results with different amount of memory do not differ ?  (Read 2891 times)

2021-07-28, 14:07:43

Dmytro

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I watched the Corona Benchmark User-Submitted Results and did not understand why they do not differ for different memory sizes.

For example from my experience I have the following builds and results:
 1. TR 2990wx and 128Gb RAM, result: 40 sec
 2. TR 2990wx and 96Gb RAM, result: 52 sec

But if you look in Corona Benchmark User-Submitted Results the results for 64Gb RAM and 128GB may be the same. (attached file with screen)

I don’t know any settings?
« Last Edit: 2021-07-28, 14:11:17 by Dmytro »

2021-07-28, 14:15:04
Reply #1

Ryuu

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The size of memory plays a role only when you don't have enough of it. If your scene (and all other programs you're running at the same time) fits in the available memory, there should be absolutely no difference between various RAM sizes.

There are other factors which come in play, because I guess the two builds you mention are not exactly identical. For example the RAM in the 96 GB build might be running on lower frequency or be configured in a way that not all the CPU memory channels are used. And that's talking just about memory, there can be many other factors affecting computer performance, not just hardware, but also any currently running software as well.

2021-07-28, 14:16:14
Reply #2

TomG

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Memory doesn't help things go faster, unless you run out :) And if you run out, things then go very much slower.

There may be other differences between those two machines (BIOS, motherboard, timings, various performance overrides and tweaks) that are the cause of the difference. You will find plenty of results on the benchmark where the CPU and memory are the same, but the time to complete the benchmark is different, sometimes by quite a lot, and this is due to those other aspects of the hardware set up.
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2021-07-28, 14:26:44
Reply #3

Dmytro

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The size of memory plays a role only when you don't have enough of it. If your scene (and all other programs you're running at the same time) fits in the available memory, there should be absolutely no difference between various RAM sizes.

There are other factors which come in play, because I guess the two builds you mention are not exactly identical. For example the RAM in the 96 GB build might be running on lower frequency or be configured in a way that not all the CPU memory channels are used. And that's talking just about memory, there can be many other factors affecting computer performance, not just hardware, but also any currently running software as well.

it turns out that the memory frequency plays a strong role for corona render ?

2021-07-28, 14:29:25
Reply #4

Nejc Kilar

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The size of memory plays a role only when you don't have enough of it. If your scene (and all other programs you're running at the same time) fits in the available memory, there should be absolutely no difference between various RAM sizes.

There are other factors which come in play, because I guess the two builds you mention are not exactly identical. For example the RAM in the 96 GB build might be running on lower frequency or be configured in a way that not all the CPU memory channels are used. And that's talking just about memory, there can be many other factors affecting computer performance, not just hardware, but also any currently running software as well.

it turns out that the memory frequency plays a strong role for corona render ?

it turns out that the memory frequency plays a strong role for corona render ?

With Zen and Zen+ CPUs it afaik does. Zen 2 and Zen 3 not so much.

Imho what you are likely seeing here is that certain configurations have faster memory / proper multi-channel configs and possibly some sort of OC going on while others don't. I didn't own the 2990wx myself but if I recall correctly that particular CPU was very picky with not just the memory speed but also multi-channel setups. Do note that you can't really go higher than a certain RAM speed anyway because of the infinity fabric and how that works.
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2021-07-28, 14:35:48
Reply #5

Dmytro

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The size of memory plays a role only when you don't have enough of it. If your scene (and all other programs you're running at the same time) fits in the available memory, there should be absolutely no difference between various RAM sizes.

There are other factors which come in play, because I guess the two builds you mention are not exactly identical. For example the RAM in the 96 GB build might be running on lower frequency or be configured in a way that not all the CPU memory channels are used. And that's talking just about memory, there can be many other factors affecting computer performance, not just hardware, but also any currently running software as well.

it turns out that the memory frequency plays a strong role for corona render ?

it turns out that the memory frequency plays a strong role for corona render ?

With Zen and Zen+ CPUs it afaik does. Zen 2 and Zen 3 not so much.

Imho what you are likely seeing here is that certain configurations have faster memory / proper multi-channel configs and possibly some sort of OC going on while others don't. I didn't own the 2990wx myself but if I recall correctly that particular CPU was very picky with not just the memory speed but also multi-channel setups. Do note that you can't really go higher than a certain RAM speed anyway because of the infinity fabric and how that works.

proper  multi-channel configs are something new for me. I always thought this is the default behavior of the motherboard and they cannot be changed.
So what can I do?
Do I need to google how exactly to change the multichannel settings of specific motherboard?

2021-07-28, 15:58:01
Reply #6

Nejc Kilar

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Sorry maybe I was a little unclear with that sentence. I'm basically referring to single, dual or quad channel memory set ups. If you've got 1 or 3 sticks in there it might be affecting the performance of the 2990wx. Again, I'm not exactly sure by just how much although I think I remember the 2990wx played "optimally" in a quad channel configuration.
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2021-07-28, 18:05:40
Reply #7

Dmytro

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Sorry maybe I was a little unclear with that sentence. I'm basically referring to single, dual or quad channel memory set ups. If you've got 1 or 3 sticks in there it might be affecting the performance of the 2990wx. Again, I'm not exactly sure by just how much although I think I remember the 2990wx played "optimally" in a quad channel configuration.

I see. Thank you a bunch!