I have the 8" Picade screen, and have the following output
pi@retropie ~ $ tvservice -m DMT
Group DMT has 1 modes:
(prefer) mode 4: 640x480 @ 60Hz 4:3, clock:25MHz progressive
pi@retropie ~ $ tvservice -s
state 0x120006 [DVI DMT (4) RGB full 4:3], 640x480 @ 60.00Hz, progressive
Detailed output - which suggests 800x600
HDMI:EDID best score mode is now DMT (9) 800x600p @ 60 Hz with pixel clock 40 MHz (score 5086400)
But if I try editing the config.txt to
The screen often flickers.
Should I be changing something to force 800x600?