MadCoder

I'm very aware of HDMI's protocols and limitations. However... Hardware restrictions wasn't mentioned, or even considered seeing that the original post was about a 4K display which assumes the end user must, or should have, decent hardware installed to get the intended performance. I ship about 5-10 custom builds a week and this is the most common issue I see once it arrives and the customer hooks up their build to a new 4k which will make make the GPU adjust. What's really nuts is when a $4k custom builds maxes out at 12FPS in mame because the customer has a $75,000 99" 16k QLED TV.

It's not a GPU, Cheap TV or hardware issue. It's actually pretty simple. The refresh rate of your 4K usually around 29-30Hz, while your emulator and OS are defaulting to higher 60Hz. You need to ensure GOU Scaling is turned off, and your internal resolution and OS resolution are the same. Example below:

Sega Master System Marquee set View File No-Intro based Marquee set for Sega Master System Submitter MadCoder Submitted 08/19/2020 Category Game Marquee Images  

Super Nintendo Entertainment System Marquee Set View File Complete No-Intro SNES Marquee set Submitter MadCoder Submitted 08/18/2020 Category Game Marquee Images  

Sega Genesis Marquee Set View File No-Intro marquee set for Sega Genesis Submitter MadCoder Submitted 08/18/2020 Category Game Marquee Images  

Atari 5200 Marquee Set View File Complete Marquee set for No-Intro Atari 5200 Submitter MadCoder Submitted 08/18/2020 Category Game Marquee Images  

Atari Lynx Marquee Set View File Complete No-Intro set for Atari Lynx Submitter MadCoder Submitted 08/18/2020 Category Game Marquee Images  

Nintendo Entertainment System Marquee Set View File Complete No-Intro Marquee set for NES Submitter MadCoder Submitted 08/18/2020 Category Game Marquee Images  

NEC PC ENGINE Marquee Set View File NEC PC Engine Marquee set - No-Intro Collection Submitter MadCoder Submitted 08/18/2020 Category Game Marquee Images