Warning : Nun samples per thread reduced to 253363, rendering might be slower

V-Ray V-Ray GPU V-Ray GPU :: General
1

Why does this happen? The scene still rendered, just curios if it would have been faster. Not sure what this warning refers to.

Anybody know what this means?

2

check your gpu ram usage, i usually got that when its using more ram than the gpu had

3

what happens if it uses more ram than it has availble? It always ends up rendering

4

it takes longer

5

Refer to this thread for an answer.

6

Just took a look at the thread @hermit.crab . So is this something I should try to fix? I have a 3080 and only do interior scenes. Should I be concerned with the warning and get a gpu with more vram or just leave as is. I want to be able to render as fast as possible with my current gpu

7

Had a laptop with a 3080 and it ran out of vram regularly…purchased a egpu with 3090 and never had any issues again.

8

@Luma3d I’ve heard mixed revies on egpus but nothing specified for rendering. Is there any drawbacks on egpus in your opinion?

9

Nope…it allowed me to keep working on projects that the 3080 couldn’t handle. The only thing that comes mind is that they are loud, but so was my MSI. TIP: Don’t use MSI laptops…they suck. Had too many problems with it.

10

Awesome, thanks for the tip

11

hi, I am using a precision 7680, 64GB, RTX4090 and it does this too! Is it my model?

12

Hi Fahad, and welcome to the forums,

It is a dangerious warning, you might be losing a lot of performance
Please take a look at my guide for optimizing GPU memory

Best,
Muhammed

13

Where would I find that - can you please attach a link?

14

Here you go - LINK.

15

@Muhammed_Hamed Thank you for your guide on optimizing GPU memory, it is a great help. I have a question about the LC subdivs. When are high subdiv numbers required? I have a complex airplane interior with lots of lights and small windows. Is it helpful to use a high LC subdiv number as a basis for further final calculation to keep the noise low?

16

Hi @Micha

I suggest using 3000 LC Subdivs for interior scenes, although you need to keep an eye on GPU memory usage as LC Subdivs have a big impact on that.
If you render in higher resolution, more than 4k you can go higher than 3000 Subdivs as long as you have GPU memory to work with

Best,
Muhammed

17

Chiming in…

I frequently see that warning pop up, but I’m almost never out of vram. In fact it just came up on a render that’s running right now, and I’m only using 7.31GB and 7.96GB of vram on 2x 3090’s with NVlink so there should be PLENTY of memory to go around. What else can have an effect on this? Does render resolution play a part? I’m running a panorama at 6,000 x 3,000.

18

Please check VRAM usage with Task Manager or GPU-Z not the stats tab, this error only happens when getting close to the GPU memory ceiling
Maybe GPU LC doesn’t have enough samples, GPU memory usage peaks near the start of the rendering when GPU LC get calculated

Best,
Muhammed