How to Enable DDC/CI on Your Monitor
DDC/CI is the switch that lets an app on your PC change the real brightness and contrast of your monitor. It takes a minute to turn on — if you know where the monitor maker hid it.
What DDC/CI is
DDC/CI (Display Data Channel Command Interface) is a VESA standard. It lets the computer send commands such as “set brightness to 40” to the monitor over the normal display cable — HDMI, DisplayPort or USB-C. The monitor treats them like presses of its own buttons. Nothing is installed on the monitor and nothing changes permanently.
How to switch it on
- Press the menu button or joystick on your monitor to open its on-screen menu.
- Look in a section called System, Setup, Other or General.
- Find the entry DDC/CI and set it to On.
- Leave the menu. If an app still does not see the monitor, switch the monitor off and on once.
Where it usually sits on popular brands (menus differ between models):
| Brand | Typical location |
|---|---|
| Dell | Menu → Others → DDC/CI |
| ASUS | Menu → System Setup → DDC/CI |
| BenQ | Menu → System → DDC/CI |
| Other brands | System / Setup / General — some models have DDC/CI always on, without a switch |
Still not working? Check these
- Connect directly. Docking stations, USB-C hubs, adapters and KVM switches frequently block DDC/CI. Try a direct cable to the graphics card.
- Try the other port. Some monitors handle DDC/CI on DisplayPort more reliably than on HDMI, or the other way round.
- Update the graphics driver. Old drivers occasionally mishandle the channel.
- Laptop screens do not use DDC/CI. Their brightness goes through Windows instead — ArrayLux handles both automatically.
Once it is on
Open ArrayLux and every compatible monitor appears with its own brightness and contrast slider. From there you can control all monitors at once or dim below 0%.