I have geovision 8 channel system and i have reformatted the hard drive once because the system was giving blank screen often.Now sometimes i see camera 1,camera2,camera3 flicker too much and camera3 often loses video.But it comes back after some time.I donot know the problem.I have checked all the connections and power connection they seem allright.Has someone experienced similar problems.

you should first connect the cameras each straight to a monitor to isolate the issue to your either the dvr or the camera/power/wiring/connectors