- Blender.org benchmarks, have it tested, so it works and you can compare figures with other gpu
- Also note that I think that the RTX series (20xx and up) have a significant advantage of OPTIX which immediately means great viewport denoising at less than 100 samples (sometimes much less… 30 or so).
Also RTX and Optix are ongoing aggressive development and you can expect more improvements in performance with software updates, I would think. - Finally note that if you do get rather slow Nvidia CUDA gpu, you can improve the performance dramatically with E-Cycles rendering at a fraction of the time, that I can testify from personal experience it was the reason I was able to keep my GTX 680M laptop for so long! - see this animation example with 680M.
