I am not at all planning to try to build a PC. I am sorry if I gave you that impression. Likewise, I am so very sorry if it seems that I was asking for help in the wrong venue. I to am primarily “here” as a user of Rhino but recognize that seasoned users of Rhino and those developing Rhino also know about the hardware to use, how to use and avoid using with Rhino. Nathan and your advise about the NVLink is invaluable. I do my very best to be extremely respectful of this community thus try to only post accordingly. I suspect that like most here - like you- I try to help others if I can.
My goal is to try to learn more about how to configure the GPU part for a new machine and as I mentioned to Bimo Adi Prakoso and Terry that is why I looked at this tread.
@litwinaa I used the PCI riser because I can’t physically get three GPUs fit on the motherboard in the current case I have. The PSU (power supply unit) gets in the way. This PCI riser allows me to essentially extend the PCI port on my motherboard so that I can still install the third GPU. Current drawback is that I can’t close my case, as the third GPU is dangling outside the box. Or not really dangling, I did support it with a cardboard box ;), but it obstructs the side panel of the case.
Regarding caustics: there is some experimental work in the upstream main branch. I suppose that this gets improved upon in the coming few weeks and months. When such a feature becomes available in upstream Cycles it most likely will flow also eventually into Rhino.
You said you use P4000 now without any issue. And I believe your A4000 should be too.
Okay, while this might seem strange for some, I recommend you to try few older version of Nvidia driver, that is compatible with your Win 11. I’ll look further info for this in Nvidia logs.
I remember when I did some trial and error, mixing old nvidia drivers with newer one just to make my Tesla K10 working along with Quadro M1000M and T1000, there were some issues on some driver releases as either K10 or the Quadro couldn’t be detected properly by some software. However, after some efforts, they both were recognized and working properly.
Let us all know how you need anything, and we all be glad to assist, here