OC Settings ??

Hello. I'm not that experienced in monitor oc but i want to know what are the lowest horizontal and vertical (front porch, sync width, back porch, blanking, total, sync polarity) to OC a BENQ GL2460HM 1920x1080 60fps monitor?? I was using 82 hz but when I open my pc the resolution lowers and I need to make again the settings..
TY in advance.