I do a lot of work with music, and have two external 4K displays hooked up to my Mac mini. I’m using two LG 24UD58-B monitors, but I cannot get 60Hz out of them using an HDMI cable, which is then connected to a Thunderbolt 3 to HDMI Adapter. On LG’s website, it says 60Hz is only possible with a DisplayPort cable. I’m not sure which cable I would need in order to get 60 Hz on both of these monitors, so if anyone could recommend one, and which way it should be connected, I would really appreciate it. For example, would I need a Thunderbolt 3 to DisplayPort cable, with the DisplayPort end connected to the monitor, and the Thunderbolt 3 end connected to the Mac mini itself? Getting only 30Hz out of these monitors makes them feel really sluggish so I would definitely prefer to get the 60Hz out of them if I could.
I use it myself to run a 4k Dell monitor with 60hz, and it works flawlessly. You are right that most HDMI adapters don't support 4k with 60hz, although the official specification supports it theoretically from HDMI 2.0 onwards. Using the mentioned USB-C to DP cable solved this issue for me.