I had real trouble with iRay, Daz 4.14, NVIDIA driver version 457.3, 8GB 2070 using Kaluma's gens. iRay gets stuck in an endless loop when I add it to the figure. Each iteration looks like this:
2020-11-27 17:24:57.204 Iray [INFO] - IRAY:RENDER :: 1.0 IRAY rend info : Initializing OptiX for CUDA device 0
2020-11-27 17:24:57.766 Iray [INFO] - IRAY:RENDER :: 1.0 IRAY rend info : Rendering with 1 device(s):
2020-11-27 17:24:57.771 Iray [INFO] - IRAY:RENDER :: 1.0 IRAY rend info : CUDA device 0 (GeForce RTX 2070)
2020-11-27 17:24:57.771 Iray [INFO] - IRAY:RENDER :: 1.0 IRAY rend info : Rendering...
2020-11-27 17:24:57.842 Iray [INFO] - IRAY:RENDER :: 1.0 IRAY rend info : Updating geometry.
2020-11-27 17:24:57.842 Iray [INFO] - IRAY:RENDER :: 1.0 IRAY rend info : Updating motion transforms.
2020-11-27 17:24:57.842 Iray [INFO] - IRAY:RENDER :: 1.0 IRAY rend info : Importing scene graph.
2020-11-27 17:24:57.854 Iray [INFO] - IRAY:RENDER :: 1.0 IRAY rend info : Auto instancing compression ratio 1.00 (Full instancing compression ratio 1.00)
2020-11-27 17:24:57.854 Iray [INFO] - IRAY:RENDER :: 1.0 IRAY rend info : Importing geometry for motion time 0
2020-11-27 17:24:57.868 Iray [INFO] - IRAY:RENDER :: 1.0 IRAY rend info : Geometry import (1 triangle object with 162k triangles, 0 fiber objects with 0 fibers (0 segments), 1 triangle instance yielding 162k triangles, 0 fiber instances yielding 0 segments) took 0.013s
2020-11-27 17:24:57.873 Iray [INFO] - IRAY:RENDER :: 1.0 IRAY rend info : Updating materials.
2020-11-27 17:24:57.881 Iray [INFO] - MATCNV:RENDER :: 1.0 MATCNV rend info : found 187 textures, 0 lambdas (0 unique)
2020-11-27 17:24:57.885 Iray [INFO] - IRAY:RENDER :: 1.0 IRAY rend info : Updating lights.
2020-11-27 17:24:57.885 Iray [INFO] - IRAY:RENDER :: 1.0 IRAY rend info : Updating object flags.
2020-11-27 17:24:57.885 Iray [INFO] - IRAY:RENDER :: 1.0 IRAY rend info : Updating caustic portals.
2020-11-27 17:24:57.890 Iray [INFO] - IRAY:RENDER :: 1.0 IRAY rend info : Updating decals.
2020-11-27 17:24:57.892 Iray [INFO] - IRAY:RENDER :: 1.0 IRAY rend info : Allocating 1-layer frame buffer
2020-11-27 17:24:57.897 Iray [INFO] - IRAY:RENDER :: 1.0 IRAY rend info : Using interactive scheduling, caustic sampler disabled
(no error, just restarts at the top)
After some experimentation I determined it's related to geometry resolution. The base resolution is kind-of high (that's very nice for morphs!) and default high resolution in viewport is subdiv 2, but for render it's subdiv 4. I have a feeling it's generating a couple of billion triangles in there which is why iRay doesn't like it with my card. Something I'm not sure about is the "1 triangle instance yielding 162k triangles" thing. If that's the tessellation then yes, Render SubD is something you really have to pay attention to with this gen.
One more thing on female gens in general, for me personally the most important thing is to be able to make my own morphs. To this end I like to be able to select and freeze labia minora/vagina out from the majora so I can work on them separately, which I can do fairly easily with this gen but not so easily with anyone else's.
Thanks.