Hi
Just got the second 3090 added to my system and while the Octanebench is showing that the speed has increased
I am not getting any feedback that the second Video Card is used in the Performance tab of the Task Manager when rendering in Blender.
Dual 3090 GPU Usage
if You want to see real load on the card, switch to CUDA in windows task manager or simply install MSI afterburner - it will give You correct load and You will see much more metrics.