What settings are you running on each cards respectfully?
I have both of those O_o
currently im running the 2 asus cards on 70/70/+292/-502/75M and the 2 gigabyte cards on 68/70/+197/-502/75M.... currently have them mining skein... since my other rigs managed nearly 13/day/per card today on zpool... im up to 12 gtx1080ti's now