LC and Nvlink question

[vishwanath_mani]

Hello. I Have some questions, hope to get a reply.

1. Is it best practice to use LC in vantage or disable it ? If we disable it does it use only BF method ?

2. Do the settings in render panel only effect the display image which is rendered in viewport ? or does it effect the render high quality snapshot and sequence in tools menu when your doing the final rendering ?

3. I have 2x 3090 24GB RTX cards, it has nvidia nvlink attached.
a. should i enable SLI mode ?
b. if yes, then does it support doubling on ram, (in my case 48gb)

Thank You

[npg]

1) Light cache speeds up rendering. It may produce some artifacts. In this case you could increase the light cache "sample limit" to try to improve its quality. If LC is turned off we render BF, yes. Note that this LC is not quite like in V-Ray, for example it doesn't trace to a great depth, it only caches at the BF depth.

2) Yes, Render panel applies to both interactive and "offline" rendering.

3.a) NVLINK (SLI) mode could increase the maximum possible framerate that you can get when using two cards. This is because the bus between the two is a bottleneck and if the GPU manages to render fast enough (scene dependent) it ends up waiting for the data transfer between the two cards. So if your scenes are heavy enough to keep the GPU busy for a long time (e.g. 10 fps) there would be no significant difference as the transfers would complete in time even on PCI-e. Maximum FPS is resolution dependent.

3.b) Unfortunately not yet. We don't share memory between the two GPUs. In fact, a bit of additional copy buffers are used on the main GPU in dual GPU mode.

[vishwanath_mani]

Thank You for Quick Reply