Configuring multi-gpu environment in ubuntu 18.04

Hello, I used to operate system with only one RTX2080, but I connected the RTX3080 for multi GPU environment. The NVIDIA driver installed is shown in the picture below.

Is the RTX3080 not shown in NVIDIA-SMI because the CUDA version does not match the current NVIDIA driver? Is it right that it is shown in the multi-GPU environment because it is the first time?

Is it right to configure the environment again to operate multi-GPU?

Anyone who help me?

I solve it. my mistake is nvidia-driver-{version}