Adjust the performance capability of GPUs

Hi all,

I have 3 gpu cards and successfully installed the Nvidia driver and CUDA.

As you can see in the pic shown below, GPU 0 and 1 are installed in the PCIe X16 slots directly on the motherboard and GPU 2 is installed via eGPU box connected through thunderbolt 3 port.

Since I want to adjust the performance capability to max for all the 3 cards, I do NOT know why GPU 2 is missing in the Nvidia X Server Setting window, while, by using nvidia-smi in the command line, 3 cards are shown.

Or, is there any way to adjust the performance capabiligy of 3 cards through commands?

Thank you in advance.