For now, I've got a NVidia GTX 2080Ti and a NVidia GTX 3090. I prefer using an external GPU racks to hold multiple GPUs at different generations, say:
  • one GTX 2080Ti
  • one GTX 3090
  • one GTX 4070 (in the future)

Any recommendations for those external racks?
And, how to connect the rack with my motherboard?

Thank you ...