I have an old BenQ 2720Z with newer firmware (above V2). I am saving up for something with 165 or 240Hz at the moment but wanted to try to overclock my monitor. I created a custom resolution with CRU and the 165Hz overclock works fine, and I can feel the difference playing counterstrike.
Two problems:
1. How can I "calculate" or find the settings for Front Porch, Sync Width, Back porch, Blanking and/or Total? Also, polarity?
2. I am not sure if this problem came with the overclock, but it is here to stay as far as I can tell. For some days now, I can see small white lines on my monitor (left to right) which fill 85% of the screen and then stop. After this line, the lines disappear and the panel also has more contrast in the area.
I tried taking a photo of it, but it is rather hard with a phone. You can't really see the lines. The strong black bar on the top is just the Photoshop window. I am talking about the change in gray below.

Maybe someone can help me out or clear things up for me. A lot of stuff here is too technical for me.
Thanks a lot!