@ivwshane /recalbox/system/recalbox.config
I personally have it set to 720p, as there is no point in wasting cpu power rendering these games at 1080p, and at 1080p, a lot of shaders will slow the device down, whereas they work fine at 720p
Also, as per inside that file, you must stop the N64 and Dreamcast rendering at even 720p.
These lines are there, probably preceded with a ; so they don't take effect. That semi colon must be removed, and the lines need to be:
system.es.videomode=CEA 4 HDMI
Thats near the start
global.videomode=CEA 4 HDMI
Thats probably around line 300
n64.videomode=CEA 4 HDMI
dreamcast.videomode=CEA 4 HDMI
Those 2 will be around line 400 ish