How to improve dual vs single GPU render times

[pedromdadgostar]

Hi - I have two 3090's in my rig. I'm seeing pretty consistently only about 1.4 - 1.5x improvement over just one GPU.

I don't think there are any major bottlenecks in the system to cause this.

No NVLink at the moment

[infoXSUUB]

Interesting. Would be great to have an answer to this. Nvlink is also very hard to get for a decent price now

[infoXSUUB]

same here, let's keep this thread alive, I think it's important for the team to get the most out of a multi card rig

[schwungsau]

it would help if you had a high-speed CPU (5Ghz) to feed the GPU fast enough with data. plus a motherboard with enough PCI lanes.
also, most people forget about the heating problem.

[miro.digital]

That has been a problem since Arnold GPU’s first release, no solution since then. I also have 2x3090 installed and Arnold using only 40-50% of both cards. Doesn’t really go higher in utilization - in comparison Redshift/Vray/Octane uses well above 90% all the time. Unfortunately the issue has nothing to do with PCIe lanes, CPU or cooling.