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

[Muhammed_Hamed]

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?

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

[charles_messenger]

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.

[Muhammed_Hamed]

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.

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