How to Configure U2415 Monitor Daisy Chaining on Intel HD Graphics
Summary: This article addresses a configuration requirement for daisy-chaining Dell U2415 monitors on Intel HD Graphics.
Symptoms
Multi-Stream Transport (MST), also known as Daisy Chaining, is a new connection specification that allows multiple monitors to be connected in series with the video signal being passed from the computer to a monitor, and then from the first monitor on to the second monitor and so on.
This differs from the traditional configuration of having a separate video cable run from the graphics adapter to each monitor in parallel. This simplifies the video wiring in most situations, but does have some specific configuration requirements to enable it.
Cause
Daisy chaining monitors is supported in the Display Port (DP) 1.2 specification, however, not all the monitors to be included in the daisy chain configuration can be set to DP 1.2 due to how the Intel HD Graphics Driver functions. In order to enable Daisy chaining, the first monitor in the series (the monitor directly connected to the graphics card) must have DP 1.2 enabled in the monitor settings. The last monitor in the chain must have DP 1.2 disabled.
The reason for this is that the Intel HD Graphics driver requires a "terminator" signal in the chain to indicate the last monitor is the last monitor in the chain in which to extend (or duplicate) the desktop to. If there are three monitors in the daisy chain, then the first two monitors would have DP 1.2 enabled and the third would be disabled, and so on.
DP1.2 enables MST streaming. To the Intel HD driver, leaving it turned off behaves like a terminator in the chain. You may extend the desktop to the monitors with DP1.2 enabled, but can only clone any additional monitors beyond the terminated monitor.
Resolution
To configure daisy chaining for three (or more) monitors:
- Extended:
- Select On Screen Display (OSD) the DP1.2 enable/disable feature. Set the first monitor to DP1.2 enabled, set the second monitor to DP1.2 enabled and set the third monitor to DP1.2 disabled (if the third monitor is the last monitor). The first display will be your primary display and the 2nd and 3rd displays will be extended.
- Cloned:
- Select On Screen Display (OSD) the DP1.2 enable/disable feature. Set the first monitor to DP1.2 enabled, set the second monitor to DP1.2 disabled and set the third monitor to DP1.2 disabled (and so on). The first display will be your primary display and the 2nd and 3rd displays will be cloned.
Users can locate additional configuration details in the U2415 Monitor User Manual.