You can't change refresh rate in Xvesa, because it was designed only for 60 Hz.
You have to install Xorg and set in xorg.conf correct refresh rate range.
for exampleSection "Monitor"
Identifier "NEC MultiSync FE2111SB"
VendorName "NEC"
ModelName "FE2111SB"
HorizSync 30 - 80
VertRefresh 50 - 70Option "dpms"
EndSection
but I don't know what to do next, because I was always using KDE to change refresh rate. Maybe
xrandr will help.