Hello Julien999,
Currently PhotoScan supports GPU utilization for the image matching and depth maps calculation stages, so if you are processing large datasets and are generating the dense clouds in at least Medium quality, then you should have at least one fast GPU that will speed up the mentioned steps.
GTX 1080Ti according to the specifications should be about 4-5 times faster than GTX 1050Ti in terms of PhotoScan performance. But you can also check less expensive cards, taking into consideration the number of CUDA cores as a main performance factor.
As for CPU, I don't think there's a need to switch to 7940X, since your CPU is already close to the optimal parameters - reasonable number of CPU cores and quite high CPU frequency.