2nd GPU just for displays?

[trick]

There are some conflicting opinions among the people around me about the need for a 2nd GPU. I have a workstation with an RTX4090 which of course is chosen for interactive speed in GPU apps like VRay, Vantage, Twinmotion, D5 Render. Now with 2x 32" 4K monitors, would it make sense to put a 2nd GPU just for display purposes to relive stress from the 4090? IS there any significant speed gain?
What GPU would be best (also with regard to modeling in FormZ, Max, Rhino, ZBrush), with one eye on energy consumption: RTX4060, RTX2000/4000 ADA (/SFF) ?

Some say speed and memory consumption on the 4090 will be better...others say both will be negligible...Personally I would like to avoid a 2nd GPU.

[glorybound]

Yes, Choas told me that a second GPU for MAX and your display is a good idea. This leaves the 4090 100% for V-Ray.

[trick]

Bobby,

Any idea where I can find specifics?

[francomanko]

Firstly, having a second gpu soley for rendering, means that none of the ram of that card is used by anything else thats running on your pc. Secondly when rendering with a single gpu, viewport performance suffers, which i found after a while quite annoying. I would definately recommened keeping a second gpu purely for rendering.

[trick]

I will be testing an RTX4060 and a RTX4000 ADA next to the RTX4090 to see if it makes any difference. I did this once with 2x1080TI's in the past and it did not make that much difference: sure total rendering speed is faster, but starting/initializing on adjusting materials/moving objects actually was a bit slower, which made the whole process quite disappointing. This was with both cards activated for GPU rendering, because I didn't purchase the second 1080 just for display. This time the second card will only be for display purposes, while only the RTX4090 will be for rendering.