Dual GPU setup for rendering?

After sticking with the same setup for X years, I finally decided it was time to overhaul my video editing rig. Here’s what I picked up:

Intel Core i9
ASUS ROG
Corsair Vengeance
Nvidia RTX 4000 8 mb

Right now, the machine is still running an old Nvidia GeForce GTX. Once I swap everything out, I have a bit of a question:
Is it actually possible to pair these two cards so they work together on specific rendering tasks—like Optical flow—where programs such as Handbrake lean heavily on the GPU? If that's a thing, how would I go about setting that up on this motherboard?

Thanks in advance for any advice you can throw my way.

Betty Nelson3 said:After sticking with the same setup for X years, I finally decided it was time to overhaul my video editing rig. Here’s what I picked up:

Intel Core i9
ASUS ROG
Corsair Vengeance
Nvidia RTX 4000 8 mb

Right now, the machine is still running an old Nvidia GeForce GTX. Once I swap everything out, I have a bit of a question:
Is it actually possible to pair these two cards so they work together on specific rendering tasks—like Optical flow—where programs such as Handbrake lean heavily on the GPU? If that's a thing, how would I go about setting that up on this motherboard?

Thanks in advance for any advice you can throw my way.

In theory, you could pull that off using OpenCL mode. You might want to download LuxMark just to see how they perform individually versus how they behave when they're working together.
"Rendering" is such a broad term, isn't it? What software are you actually using? It sounds to me like you might be talking about Adobe Premiere Pro, especially if you're looking at Optical flow, where the RTX card will likely carry most of the weight on its own.