Refresh Frequency 8800GT too low

Hi everyone
I have one small problem with my LCD.
Let me explain, using VGA input in my LCD (through DVI to VGA converter) i get proper frequency (75Hz) on my LCD although the screen is fuzzy and anything but not crisp, and using VGA i can change frequencies between my LCD’s native 60Hz and 75Hz.
When using DVI i have only 60Hz ??? And can’t change it at all using nvidia-settings.
Any help appreciated please.
P.S. nvidia-settings uses xrandr to change settings or has its own proprietary tool ??