Jesse, It seems the mode is from the Sony monitor itself:
(II) intel(0): Modeline "1024x768"x0.0 65.00 1024 1048 1184 1344 768 771 777 806 -hsync -vsync (48.4 kHz)
Vincenzo, have you tried command 'xrandr --auto' after connect the VGA monitor after booting up without it?
Jesse, It seems the mode is from the Sony monitor itself:
(II) intel(0): Modeline "1024x768"x0.0 65.00 1024 1048 1184 1344 768 771 777 806 -hsync -vsync (48.4 kHz)
Vincenzo, have you tried command 'xrandr --auto' after connect the VGA monitor after booting up without it?