I've had a lot of struggles with this capture card. I was planning on returning it, and actually got in touch with the support, but I decided to keep it anyway and just use a Elgato HD 60 S in the mean time, for like 3-4 months. Then one day, I decided to try using this card again and it has been working amazing, so I wanna write up how I have it set up.
Driver: Use 22.214.171.124.5
Amarec: Use 3.10
Use these settings for the device and set up these presets in Amarec (you can also add more presets if you like, and you probably should if you capture 240p/480p):
fps=60.10(because NES/SNES runs a bit faster than standard 60Hz).
SYNC_SETis set to
AUTO, which yes, the PEXHDCAP60L suports, atleast in 720p. I think capturing 1080p60.10 was what broke mine temporarily.)
Oh, and the PEXHDCAP60L is basically the same thing as a Micomsoft SC-512, so these steps should work for that card too.