S2719DC, no daisy chain

Question

I have a S2719DC monitor and wonder if I buy another S2719DC monitor can I daisy chain them with a windows 10 laptop input from USB C cable to the first monitor. Or does this monitor not support this config. If not which dell monitor should I buy of similar visual specs to do the daisy chain to my existing S2719DC monitor?

If it can be done could you tell me which ports to use and what cables I will need.

Thanks so much for advise

jphughan · Accepted Answer

@finsmasher Unfortunately if you already have an S2719DC, then I have mostly bad news for you -- and only a little bit of possible good news. Daisy chaining requires a display that has a DisplayPort output in order to set up the chain, and then a display with a DisplayPort input to receive that signal. The S2719DC doesn't have a DisplayPort output, and it doesn't have a DisplayPort input either. That means it can't be the first display in the chain (since there's no DisplayPort output to feed the second display), and it can't really be the second display in the chain either (no DisplayPort input to receive the signal from the first display). And according to Dell's product page, the S2719DC's USB-C input only provides up to 45W of power. That isn't enough power to run most laptops at optimal performance. Most displays provide 65-95W.

The S Series displays are consumer-oriented displays. Dell adds daisy chaining support to their business-oriented displays like the P Series and U Series displays.

The additional complication with running a daisy chain of QHD/1440p 60 Hz displays when you want to connect the source system via USB-C is that if you want to use USB 3.x data over that connection as well, you need a system and display that both support DisplayPort 1.4/HBR3 over USB-C, which is still relatively uncommon. If your system and/or display only support DisplayPort 1.2/HBR2, then you need a display that can be configured to limit its USB data speeds to USB 2.0 in order to keep enough video bandwidth available over USB-C to run dual QHD 60 Hz -- and of course you need to be ok with only having USB 2.0 speeds.

Now for the somewhat good news. The Dell U2721DE is a 27" 1440p display like your S2719DC, but unlike your S2719DC, it has a USB-C port that can provide up to 65W of power, and it also has a DisplayPort output to start a daisy chain, AND it can be configured to run either DP 1.4/HBR3 plus USB 3.x if your system supports that, or DP 1.2/HBR2 plus USB 2.0 if it doesn't. And if you were to get an active DisplayPort to HDMI adapter, like this one -- NOT a much more common passive DP to HDMI adapter/cable -- you could connect the DP output of the U2721DE to the HDMI input of your S2719DC. The reason the active adapter works and is necessary is because a daisy chain requires DisplayPort protocol to be used along the entire chain. Passive DP to HDMI adapters rely on the DisplayPort source to fall back to native HDMI signaling, but you can't do that on a daisy chain. By comparison, active adapters allow the source to continue using DisplayPort protocol and perform the HDMI conversion within the adapter itself, and that's fine for sending a video signal to the LAST display in the chain because that display won't need to continue the chain to another display.

So if you get a U2721DE and an active adapter, you should be able to get your daisy chain. But depending on the system you plan to use with it, you might have to limit your USB data speeds to USB 2.0. And then you'll have to determine if 65W is enough to run your system properly.

jphughan · Answer

@finsmasher Here's another option. If you really want to have matching S2719DC displays, then another way you can leverage daisy chaining technology without needing daisy chaining support within the displays is to use an MST hub. This one connects to a USB-C port and provides 2x DP outputs and 1x HDMI output. It also has a USB-C power passthrough port. So for example you could connect the display's USB-C port to that power passthrough port to get power to your laptop, and then connect separate video cables from the MST hub to each display. Since the MST hub only has one HDMI output and the S2719DC doesn't have a DisplayPort input, you'll need to connect one of your displays using an active DisplayPort to HDMI adapter like the one I linked above. Here again, typical passive cables/adapters normally don't work on MST hubs. (Alternatively, there are MST hubs with dual HDMI outputs, but I don't know of any offhand that also have USB-C power passthrough.)

The functionality you lose with this setup is that you'll no longer have USB data connectivity between your system and the displays, which means you wouldn't be able to use the USB ports built into the displays. If you wanted to do that with an S2719DC, you'd have to connect a USB-C to USB-A cable from the display's USB-C port to a USB-A "regular USB" port on your laptop. But that would then mean you couldn't use that display's USB-C port as a power source. But since you'll have dual S2719DCs, you could use the USB-C port on one display as a power source connected to the MST hub, and use the USB-C port on the other display for USB data -- as long as you only needed to use the USB ports built into one display rather than both of them.

finsmasher · Answer

Thanks so much for your very helpful reply and advice - really clear explanation ,Thx

Monitors

S2719DC, no daisy chain

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