3rd GPU will not run in betas

[Diesel]

I've been running 2 1080ti's on 5.1-1733 using cygwin. Occasionally it will start and show copying on both devices then stop. I  recently added another gpu and it will run any 2 of them together, but when all 3 are selected it usually shows copying and stops. Rarely it will run 1 device and show the other 2 copying. I have also tried it on 5.1-1772 with the same results. It works fine on 5.1, but I lose mode 22000. I Have also removed and reinstalled drivers.