Here’s a comparison between 288p GC (perfect picture, no issues) and N64 (picture slightly blurry, mostly horizontal ghost image/blur towards the right border of the screen; sync? issues).
Both are using Generic 4:3 Line2x mode.
313p 540858 (or 840859)
AV1: RGBS 313p
AV1: RGBS 312p
OSSC on-time (warmup) doesn’t seem to affect GC, but heavily affects N64 with flickering going down from every couple of frames to something like every couple of dozen seconds.
Considering that this gets better over time, I’m wondering if there’s an issue with my OSSC. I usually associate such behaviour (issues improving or getting worse over run-time) with temperature or soldering issues. (To be fair, I don’t have that much confidence in the connectors because they have no strain relief, i.e. they are not anchored to the case, but all mechanical energy is directly transferred to the solder joints)