What people have found so far
1 verified report. Every row is real diagnostic output from a real machine — nothing inferred or guessed, which is why this list is short.
| Grade | Monitor | Mac | Connection | Volume | DDC reads |
|---|---|---|---|---|---|
| B | Samsung CF791 | Mac mini (M4) | Built-in HDMI | Works | reads broken |
How monitors are graded
Two things decide it: whether the monitor tells the truth about its own state, and whether it does what it is told.
Grades come only from behaviour that was actually measured. A monitor whose write test nobody ran stays ungraded rather than guessed at.
Which brands tell the truth?
Best grade recorded for each manufacturer's monitors.
One brand is not a pattern. This becomes worth reading at around a dozen manufacturers — which is entirely a matter of how many people run the check.
Why is the volume slider greyed out on my Mac?
Because the sound is travelling over your display cable. When audio goes out over HDMI or DisplayPort to a monitor, macOS decides the volume is the monitor's business rather than its own and disables its own control entirely. The Control Center slider greys out and the keyboard volume keys stop doing anything.
The monitor is usually still listening. Most of them accept DDC/CI commands over that same cable — a decades-old standard for telling a display to change its own settings. Whether yours obeys the volume command is entirely up to its firmware, which is why this site exists.
Three things determine the answer
- Your monitor's firmware. DDC volume support is optional and inconsistently implemented. Some monitors accept the command, some ignore it, and some accept writes while returning nonsense on reads.
- Your Mac's port. Macs with built-in HDMI convert DisplayPort using an MCDP2900 chip, and Apple cuts off the I2C channel DDC needs once the display's EDID has been read. This is why MonitorControl disables itself on the built-in HDMI port of 2018 Intel Mac minis, all M1 Macs, and the entry-level M2 Mac mini.
- What's in between. Docks, KVMs and adapters frequently drop DDC even when both ends support it.
So “does monitor X work” has no general answer. The combination is what matters, so the combination is what gets recorded here.
The case every tool gets wrong
Some monitors accept DDC writes perfectly but return garbage when asked what their
current settings are. The Samsung CF791 reports the same value for every
setting and claims its maximum volume is -128.
Most control apps read the current value before changing it, so on hardware like this they appear broken even though the monitor is fully controllable. If your report comes back reads broken, that's the bucket you're in — and it's fixable with a tool that never reads. There's one in this repo.
Questions
What does the check actually do?
Installs m1ddc via Homebrew if you don't have it, asks your display a few harmless questions, and prints a report. It changes no settings. Read it first — it's short.
My monitor isn't listed. What do I do?
Run the check and post the output. That's the entire contribution, it takes a minute, and it's the only way this list gets useful for the next person with your monitor.
My monitor says DDC works. Now what?
Use whichever tool you like — MonitorControl is free and excellent, BetterDisplay does more and handles HDMI ports MonitorControl won't. This site isn't trying to replace them; it tells you in advance whether they'll work for you.
Who runs this?
It started because one Samsung ultrawide wouldn't behave and the answer took an evening to find. It's open source and the data is a JSON file you can read.