Blender 2.91 dual GPU in 2020

At the moment, using two identical optix compatible GPU in blender 2.91 actually slows down your viewport. I just thought I would share this in case someone was going to buy a 2nd GPU and hope for a viewport performance boost.

I’m wondering if something can be done about this.

hmmm imposible, make sure your drivers are up to date…if yes then make a report to blender devs…

Thanks for your reply. I updated my drivers yesterday. My scene includes particles, transparency and some stuff. Anything else I could test? Any ideas how I could test? I just set my target viewport samples to 256 and used a stopwatch that I manually stopped when the viewport info at the top left changed to “done”. A single 3080 took around 12s. Both of them together took about 19 seconds.

Of course when rendering, it’s a different story. Using both GPU is about twice as fast.