By default the config for NES is mode 4.
# starttype==4: set video mode to 720p60
Many of the other emulators are setup for VGA only mode which is starttype==1
I haven’t actually tried adjusting this as my NES seems to run fine.
The config file is located here: /home/pi/.emulationstation/es_systems.cfg
Scroll down to this line –
DESCNAME=Nintendo Entertainment System and you will find this line
COMMAND=/home/pi/RetroPie/supplementary/runcommand/runcommand.sh 4 "/home/pi/RetroPie/emulators/RetroArch/installdir/bin/retroarch -L /home/pi/RetroPie/emulatorcores/fceu-next/fceumm-code/fceumm_libretro.so --config /home/pi/RetroPie/configs/all/retroarch.cfg --appendconfig /home/pi/RetroPie/configs/nes/retroarch.cfg %ROM%"
If you change
runcommand.sh 4 to
runcommand.sh 1, I believe that will change the video output mode, although I have tested this, just a guess that it will work but I assume that the emulator supports 480p output.