I’m not informed on the PCI specs but I bet the bottleneck is simply bandwidth (or CPU), the GPU is capable enough. I have a 2080ti as an Thunderbolt 3 eGPU, w

I’m not informed on the PCI specs but I bet the bottleneck is simply bandwidth (or CPU), the GPU is capable enough. I have a 2080ti as an Thunderbolt 3 eGPU, which has an even smaller bandwidth than PCI Express so the effect is accentuated. I lose about 10% perf on 4K compared to a desktop computer, and 40% at 1080p. I don’t recall the exact numbers but a benchmark would do 80fps on 4K and 120fps on 1080p, even though it’s 1/4th the amount of pixels. This is because most of the time is spent transferring data on the bus.