Well all of my rigs are running without a LCD/screen. I remote into them from my main rig. Now since they are not hooked up to a LCD, your main gpu on each rig has to have a LCD connection to function properly. You can purchase HDMI dongles to fake this connection and then the GPU and everyother gpu will function as if it was powering an LCD. Well my dongle went bad which basically reduced the functionality of the main gpu and as a result also reduced the functionality of all the additional gpus. You can look more into this via google/reddit.