Finally got RGB color on M1 Mac mini and Dell U2415 monitor
After months of looking for solutions and testing different overrides and workarounds, finally got RGB color working on the M1 Mac mini with the Dell U2415 monitor, connected with a simple HDMI-HDMI cable.
The workaround is pretty crazy, and here it is:
You will need 2 cables:
- 1 HDMI to HDMI cable
- 1 USB-C to DisplayPort cable
Step-by-step procedure:
- Connect BOTH cables at the same time to the M1 Mac mini and the Monitor.
- Turn on the Dell U2415
- Select DisplayPort as a source in the Dell U2415 On-Screen Display
(OSD) menu - Turn on the M1 Mac mini
- Boot into macOS as usual (tested with Big Sur 11.4)
- The M1 Mac mini will show as 2 displays connected to it, and the DisplayPort as the main display in YPbPr color. This is as expected
- Switch the source to HDMI in the Dell U2415 On-Screen Display (OSD) menu
That's it!
Your display should now show that it's in RGB color and connected over HDMI.
You can even disconnect the USB-C cable from the M1 Mac mini after this and restart it, and it should still continue to work into RGB mode from now on.
Hope this tutorial helps someone and saves them from going through all the trouble of testing many different workarounds.
Please note that I've only tested it to work with Dell U2415 and on Big Sur 11.4 RC. If you have any additional questions regarding the procedure, please feel free to ask in the comments
There is now a more advanced procedure based on this discovery that works without the need for Dual-Cables:
Force RGB Color on M1 Mac
https://gist.github.com/GetVladimir/c89a26df1806001543bef4c8d90cc2f8