XPS 13 2in1 - How Many External Monitors on One USB-C

The XPS 13 2-in-1 doesn't just have regular USB-C; it has Thunderbolt 3, and that means there's twice as much display bandwidth available if you use it that way.  When used a regular USB-C port, you have only a single DisplayPort 1.2 output available, so your display limit would be based on the maximum number of displays supported by the GPU (which I believe is 3, counting the built-in display if you have it enabled) and whether DisplayPort 1.2 has enough bandwidth to drive the external displays you want.  A single DP 1.2 output can handle two displays up to 1920x1200 @ 60 Hz, so if one of those displays is more than that, you won't be able to use it with the second display at the same time.  If you were to use it as a Thunderbolt 3 port, however, you'd have two DisplayPort 1.2 outputs available, which would let you handle dual displays each up to 4K @ 60 Hz.  You would still be limited by the total number of displays supported by the GPU, however.

But since your displays aren't native DisplayPort, you'd have a few options here.  The first would be a docking station, either the WD15 USB-C docking station or the TB16 Thunderbolt docking station, either of which would give you DisplayPort and HDMI outputs, so you could just get a DisplayPort to DVI adapter if needed. Either dock would also be capable of supplying power to the system, assuming that the XPS 13 2-in-1 can also accept power out of its display-enabled USB-C port rather than exclusively on the power-enabled port.  You should test that.  The main difference between those docks is the maximum display resolutions allowed because of the different levels of bandwidth they have available.

Alternatively if you just want display connectivity, you'd need a series of adapters. One option would be a Thunderbolt 3 to Dual DisplayPort adapter to which you would connect DP to DVI and DP to HDMI adapters.  If you go this route, you will need to make sure that the DP to DVI/HDMI adapters are both ACTIVE adapters.  Most such adapters on the market are passive, but those don't work when the DisplayPort outputs are being driven by Thunderbolt 3.  The main advantage here is that since you're using a Thunderbolt 3-based adapter here, your maximum display configuration is higher. And the second option that only uses regular USB-C (and therefore has lower maximum bandwidth) would be USB-C dongle that gives you a single DisplayPort female output, then you'd attach what's called a DisplayPort MST hub, which splits a DisplayPort output into multiple physical connectors. That's handy if you want to drive multiple displays off of a single DP output but don't have displays that support daisy-chaining or don't have displays that natively support DisplayPort.  And then you'd finally attach those DP to DVI/HDMI adapters to the MST hub's outputs.  Most MST hubs do NOT require active adapters, by the way, so you might save some cash there, but that's not a guarantee, so if an active adapter isn't much more, you might want to get it anyway just to minimize the potential for issues.

Wow!

Thanks for the detailed answer! I have to now digest it!

You're welcome!  If you have any more questions or want to post a specific proposed setup, like "I have these displays, so would these products work together?", don't hesitate to post! :)

maby a little hijacking this topic but maybe you can help me...

Ive a new xps 13 (not 2 in 1). i7, 16gb and a wd15 dock. I have have 2 Dell U2515H displays connected through displayport. From docking: mini DP --> screen 1 DP --> Screen 2 mini DP

So Im using the pass-through (don't know how to connect them both otherwise).

But on the second display the refresh rates a shockingly low, or the resolution is to low or the text on the screen isn't sharp.. I tried everything, also switching both screens...

any ideas i can try?

Hi there,

Borrowing this thread on a related topic.

I've just purchased a Samsung C34H890 monitor with USB-C support. However, when I plug it into my XPS 13 9365 directly, it is not recognized by Windows10. Using HDMI port on the monitor and a HDMI -> USB-C adapter to the laptop works. Do you know if the TB3 ports on the XPS 9365 would have issues communicating with USB-C (non-thunderbolt3) monitors for any reason?

Appreciate any help

Filipp

@Roelsrules, as explained on the WD15's product page, manual, and FAQ page, and my longer post above, the WD15 can only do dual 1080p @ 60 Hz, and the U2515H is 1440p.  The dock only gets half the bandwidth of a single DisplayPort 1.2 output, so in your setup the dock is sacrificing refresh rate and/or resolution to try to let you use the second display at all, using what little bandwidth remains after driving the first display at full capacity.  But officially, the WD15 only supports a single display at 1440p anyway.

If you want to use that setup properly, you would need a TB16 dock instead, which gives you quadruple the display bandwidth of the WD15 and therefore could handle up to dual 4K @ 60 Hz.

@filipp.blackvall, when you use a USB-C to HDMI adapter, you have a full DisplayPort 1.2 output's worth of bandwidth available.  When you connect the display through the WD15 dock, you only have half that display bandwidth available.  The reason is that using the USB-C to HDMI adapter allows all of the USB-C port's output to be dedicated to display traffic, whereas the dock uses half of the USB-C's pins to carry USB traffic to run the other devices on the dock.  The C34H890's resolution requires more display bandwidth to run than is available when using the dock, but a full DP 1.2 output is enough.  Similar to my post above, if you were to replace your WD15 with a TB16 dock, you would be able to use your display through the dock because the dock would be getting quadruple the display bandwidth from the system that the WD15 gets (and double the bandwidth that a USB-C to HDMI adapter gets because using the Thunderbolt protocol allows two full DisplayPort 1.2 outputs to be transmitted out of that port.  Regular USB-C does not.)

I explain USB-C's various modes in more detail here if you're interested: en.community.dell.com/.../20017807