The WD15 works fine on the XPS 13 and any other system that has USB-C with DisplayPort Alt Mode. It will also work with two displays, but only up to 1080p. If you want dual displays with more resolution than that, get the TB16 dock instead, which can handle dual 4K and even some triple display configurations. You might also benefit from reading the WD15's product page that explains the dual 1080p capability, and/or the Dell's "WD15 frequently asked questions" page (Google that phrase), and/or the WD15 manual available on support.dell.com.
However, with respect to dual DisplayPort, the dock only has a single DisplayPort output attached to it, and I don't know whether that output supports MST in order to facilitate daisy chaining if that's how you planned to connect your two displays. If not, does one of your displays have an HDMI input instead? Otherwise, the TB16 has both full-size and mini DisplayPort outputs built into it.
The XPS 13 will not run two 4k displays at 60 hz using a TB16 connected with DisplayPort 1.2 cables. Or rather, it will run them, but one or the other will periodically lose signal for a few seconds. The setup should work according to the product literature I've found, but it will not.
Yes, that will work. The TB16 dock gets 4x more display bandwidth out of the attached system than the WD15 does. The WD15's product page, FAQ page, and manual say that it only supports up to dual 1080p displays, although the manual mentions that you can add a third 1280x1024 display after that. I'm actually surprised you have enough bandwidth to run 3440x1440 plus a 1080p display on the WD15.
As for MST, using daisy-chaining or direct connecting each display won't matter for the WD15 because you're only getting half of a DP 1.2 connection out of the system in the first place. However, when you switch to the TB16 where you'll get 2 full-bandwidth connections, you'll want to direct attach each display. The reason is that if you daisy-chain, you'll be driving both displays off a single DP 1.2 connection from the dock, and I'm pretty sure that isn't enough for dual 3440x1440 (but I'm not certain about that). If you direct connect each display, each one will gets its own DP 1.2 connection.
And as a general best practice, disable MST on displays that aren't involved in daisy-chaining, because sometimes that will limit the display's capabilities. For example, on Dell displays that are capable of 4K at 60 Hz and have a daisy-chaining output, enabling MST causes the display to limit itself to 4K at 30 Hz so that there's enough bandwidth left over to drive another daisy-chained display, since 4K at 60 Hz consumes almost an entire DP 1.2 connection's bandwidth on its own.
jphughan
9 Legend
•
14K Posts
0
February 6th, 2018 08:00
The WD15 works fine on the XPS 13 and any other system that has USB-C with DisplayPort Alt Mode. It will also work with two displays, but only up to 1080p. If you want dual displays with more resolution than that, get the TB16 dock instead, which can handle dual 4K and even some triple display configurations. You might also benefit from reading the WD15's product page that explains the dual 1080p capability, and/or the Dell's "WD15 frequently asked questions" page (Google that phrase), and/or the WD15 manual available on support.dell.com.
However, with respect to dual DisplayPort, the dock only has a single DisplayPort output attached to it, and I don't know whether that output supports MST in order to facilitate daisy chaining if that's how you planned to connect your two displays. If not, does one of your displays have an HDMI input instead? Otherwise, the TB16 has both full-size and mini DisplayPort outputs built into it.
plivy
1 Rookie
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27 Posts
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February 13th, 2018 12:00
The XPS 13 will not run two 4k displays at 60 hz using a TB16 connected with DisplayPort 1.2 cables. Or rather, it will run them, but one or the other will periodically lose signal for a few seconds. The setup should work according to the product literature I've found, but it will not.
jphughan
9 Legend
•
14K Posts
1
April 11th, 2018 14:00
Yes, that will work. The TB16 dock gets 4x more display bandwidth out of the attached system than the WD15 does. The WD15's product page, FAQ page, and manual say that it only supports up to dual 1080p displays, although the manual mentions that you can add a third 1280x1024 display after that. I'm actually surprised you have enough bandwidth to run 3440x1440 plus a 1080p display on the WD15.
As for MST, using daisy-chaining or direct connecting each display won't matter for the WD15 because you're only getting half of a DP 1.2 connection out of the system in the first place. However, when you switch to the TB16 where you'll get 2 full-bandwidth connections, you'll want to direct attach each display. The reason is that if you daisy-chain, you'll be driving both displays off a single DP 1.2 connection from the dock, and I'm pretty sure that isn't enough for dual 3440x1440 (but I'm not certain about that). If you direct connect each display, each one will gets its own DP 1.2 connection.
And as a general best practice, disable MST on displays that aren't involved in daisy-chaining, because sometimes that will limit the display's capabilities. For example, on Dell displays that are capable of 4K at 60 Hz and have a daisy-chaining output, enabling MST causes the display to limit itself to 4K at 30 Hz so that there's enough bandwidth left over to drive another daisy-chained display, since 4K at 60 Hz consumes almost an entire DP 1.2 connection's bandwidth on its own.