I discovered today accidentally that when I'm connecting MBA M3 to my Asus VG27AQ 2K monitor with HDMI the banding on gray gradient is changing when I'm turn on and off StillColor app. Attaching photos of display.
I was surprised to see this, because I was always using DisplayPort to connect to my external display. So after that I tried the same again with my regular displayport, nothing changed, the banding stayed the same as with on or off.
So after that I was thinking maybe the HDMI I have is lower version which could not give a proper bandwidth for 2K 10bit 144hz. So I took 2.1 version from my PS5 (I hope PS5 goes with 2.1 version tho) and tried, and I again saw a banding when StillColor was ON. After that I also realized that my monitor support only 2.0 version of HDMI. I also tried to connect with some type-c dongles, so in all cases HDMI was showing those banding when StillColor was ON.
After that I went to the store to find any DisplayPort with version 1.1, but its too outdated, I think it was in years 2005-2008 so probably only on ebay I can order it for testing. So right now there is no way I can try older version, I have only 1.2.
Conclusion from my side:
- MBA M3 + StillColor ON 144hz with HDMI 2.0 -> External display: ✅ shows banding
- MBA M3 + StillColor ON 60hz with HDMI 2.0 -> External display: ❌ doesn't show banding
- MBA M3 + StillColor ON 144hz with DisplayPort 1.2 -> External display: ❌ doesn't show banding
- MBA M3 + StillColor ON 60hz with DisplayPort 1.2 -> External display: ❌ doesn't show banding
Photos for 2k 60hz with HDMI and StillColor on/off:
As you can see when I'm enabling 60hz with 2K display there is no banding on gradient, which means that the cable have enough bandwidth to send 10bit 2K signal for 60hz, but could not send 144hz and switching to 8bit. But I don't understand why I'm able to control it with StillColor app only at 144hz, is it like because the bandwidth like almost on the edge or so and the MacOS letting you do this? Or is this how HDMI implementation works right now? I remember before M1 macbooks had problems with HDMI, using old version of it.
Also when connecting monitor with HDMI in settings I can select 1920 as HiDPI, but when connecting with DisplayPort I have only 1280 as HiDPI. Weird, don't know why. And If I select 1920 with displayport the image is blurry in compare with HDMI.
From the feelings perspective, In situation when I can see bandings I'm getting weird symptoms, even more weird than when just working with laptop screen. I'm getting strange brain fog and eye strain, also slight nausea and it comes and goes away, very weird. Its also very bad when looking at this gray gradient. Hopefully this information would help somehow 🙂