GTF vs CVT monitor refresh rate best options for gaming?

if i'm doing gaming on a 1280x1024 LCD HP monitor at 60/75hz what timing should i use for the best most precise pixel frequency that should be set? i know for every monitor it's different but i just have this at the moment and want to know what i should set? the available options for custom resolution are

Pixel clock: ) Color depth (32bit)
Horizontal - Vertical
Front porch:
Back porch:
sync width:
Active:
sync polarity:
scan rate:
Total:

What should i set for the best pixel frequency that this monitor would be comfortable with using for gaming?

nobody knows? no one? plz cuz i really want to be gaming and i dont have a better monitor at the moment.

it's good enough for some of the games i play till i get something better. but i'm stuck with this monitor.
i have tried and forced higher resolutions and it seems to lock at 77hz and wont budge from anything higher. (frequency out of range at 78hz) works fine at 77hz but i don't know how to calculate it specifically to exactly 77hz to get the quickest pixel-accuracy per-pixel performance for 77hz because i think the automatic refresh rate/resolution section gets it wrong because it says "H=82.5kHz V= 77Hz" instead of just 60 or 75 or 77hz like if i just had 60hz it would say only 60hz.