Monitor does not work. I just bought a LG 1755S monitor, but when i connected in my pc, the lead

Question

I just bought a LG 1755S monitor, but when i connected in my pc, the lead indicated only "energysave" . I call LG assistence and they said to change in my BIOS the herts from 60 to 75 hz and and screen size to 1250 x 1440 pixels My mother board is a M825VXX and I cant find where to change this setup. Do you think that you can help ! tks in advance