I have 2 intel B580 arc. I have both in the server. Will plex utilize both of them if I dont select one for transcoding and leave the setting AUTO? I should also note that its using the CPUs AMD Radeon Graphis on Auto. Ryzen 9 9950x.
No. PMS only uses 1 gpu. With auto, PMS will use whatever your computer defaults to as the primary. The drop down lets PMS override the primary and use the selected one.