Hi guys

Can you try install older Nvidia drivers like 388.13 or so(if you are running Turing RTX or GTX series you can't use these drivers) , with these drivers I have good experience in rendering with "older" GPUs like GTX1080Ti or GTX1080

Can't comment on 11.3, I'm still on 11.2 and didn't tried new update for RTX, which I will be installing later on and see what difference it will makes like on GTX GPUs and RTX

What I tested few months back, older drivers do work better for GTX cards in rendering like in Octane or Cycles or E-Cycles, with newer drivers not sure why performance is not really there

I have run for long time 388.13 drivers till I got RTX 2080Ti with which I can't use these drivers sadly and performance tanked for me in Cycles or E-Cycles and few other renderers with latest Nvidia drivers branch

For me personally 388.13 have been best drivers for GTX1080Ti and GTX1080's and lastly can you use SIV64 and check GPU usage and do you have enabled progressive and how many buckets are you using?

For GTX1080 or GTX1080Ti try 384 or 512 as for bucket size,you can try download some of my scenes and test them in Poser, usually I have included like render settings and light sets which should help a bit and can you post yours times

Hope this helps

Thanks, Jura