How to daisy-chain multiple monitors from a single cable
Most people consider DisplayPort to be the premium alternative to HDMI on PCs. But while it’s generally the best connection to use with a computer monitor, DisplayPort offers much more than meets the eye.
DisplayPort was designed to scale beyond a single display
From the start, DisplayPort was meant to be more than just a point-to-point connection. Although given the way most of us use our DP devices, you’d never know it. With all that bandwidth available, there’s more than enough to theoretically drive multiple displays using a single cable.
However, as you’ve probably already realized, even if your computer has multiple DisplayPort outputs, you typically only have one DisplayPort on your monitor. Well, this is one of the main reasons why most people don’t know about this particular DP superpower. The feature is known as MST or Multi-stream transport. A monitor must support MST to allow running multiple monitors from a single cable.
Monitors supporting MST have a DP out port, which you can use to connect to the next monitor in the chain. Each monitor extracts its video stream from the cable, then transmits the rest.
Daisy-chaining eliminates cable chaos
If you’ve ever had a three or four monitor setup, you know how complicated cabling can be. Having three or four cables running from your computer to the monitors, there are only so many cable management tricks you can use to tame everything.
Serial daisy chaining allows you to manage a single long cable, at least in reality. If you pay attention to the length of cables or hide them well behind your monitors, no cables should be visible.
Not all DisplayPort configurations are created equal
MST may be a feature of DisplayPort, but as I mentioned before, you need explicit support for MST in the hardware you’re using, and that can get a little complicated.
MST was added with DisplayPort 1.2, but that doesn’t mean all DP 1.2 graphics cards support it. For more modern cards released after around 2013, MST should be supported, but it’s worth confirming if in doubt.
I’ve already mentioned that you need a monitor with MST and a DP output port, but not all monitors need to have this feature. The terminal monitor can be any DisplayPort 1.2 or later model.
The lowest version of DisplayPort you use determines how many monitors you can use and at what resolution you can drive them. DP 1.2 should handle two 1080p displays, DP1.4 can handle up to three 4K monitors, if you run one at 60 Hz and the other two at 30 Hz. With DisplayPort 2.1 you can have two 4K displays at 144 Hz or three 4K monitors at 60 Hz. You get the general idea.
Should you use HDMI, DisplayPort or USB-C for a 4K monitor?
HDMI, DisplayPort, USB-C, and Thunderbolt are all common now, but which is best?
Even if you don’t have a monitor that supports MST and can’t daisy chain it, you can still benefit from DP MST by using an MST hub. These can use a single DP input or USB-C port in DP Alt mode, then split the signal across multiple ports. Typically, an MST hub splits its input into three DP outputs.
This doesn’t provide all the benefits of serial cable management, but it still means that only one cable needs to go from your computer to your monitors. This is useful if you have a GPU or laptop with a single DP port.
This is a killer feature for laptops and productivity platforms
These days, laptops are powerful enough to be most people’s primary computer, but they have some limitations when it comes to peripherals. You won’t find multiple dedicated display outputs on a typical laptop, especially not the thin and light models that people tend to favor.
Laptops tend to have USB-C or Thunderbolt ports that support DP Alt mode, or in some cases (like my own Windows workstation laptop), a mini-DP connection. Using MST, you can simply connect with a single cable and have a multi-monitor setup up and running in seconds.
Unfortunately, as of this writing, macOS does not work this way. Although Macs have the hardware to support MST, macOS does not support extending a desktop using MST. If you were to connect an MST hub to a Mac (from what I’ve read, I haven’t tried it), you’ll just get multiple mirrored versions of the same stream.
HDMI still can’t really compete here
HDMI is also a great standard, it’s much more common and it can compete with DP on a single monitor in features and performance. However, it just doesn’t have anything comparable to MST. If you want to connect three HDMI monitors, you will still need three cables and three outputs.
But who knows, maybe it’s something that will be added to the HDMI standard one day. For now, it’s a superpower that only DisplayPort benefits from.
