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U2720Q, daisy chain third one?
I currently have three U2720Q running from a ThinkPad USB Type-C dock. The third U2720Q is connecting directly into my laptop.
Is there any way to daisy chain my third U2720Q so I don't have to unplug the HDMI cable?
There is so much contradicting information whether U2720Q are daisy chainable.
Thanks all appreciate the help.
DELL-Chris M
Community Manager
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May 16th, 2021 11:00
The confusion stems from the fact that the $1999.99 UP2720Q has a Thunderbolt downstream port to facilitate the daisy chain to another UP2720Q Thunderbolt upstream port.
The $699.99 U2720Q does not have the required Thunderbolt downstream port nor does it have a DP out port. So a daisy chain is not possible.
jphughan
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May 17th, 2021 06:00
@Shadyz82 The U2720Q doesn't have a DisplayPort output to facilitate a daisy chain in the first place, so no you couldn't daisy chain one of those to another for that reason alone. And even if you could, of the few 4K 60 Hz displays on the market that I know of that offer daisy chain outputs, most of them only support DP 1.2/HBR2, which only supports enough bandwidth for a single 4K 60 Hz display, and therefore if you daisy chain them, both displays run at 30 Hz instead. DP 1.4/HBR3 can run dual 4K 60 Hz from a single interface, so if your entire setup supported that, then you could run dual 4K 60 Hz in a daisy chain, but I haven't seen a 4K 60 Hz display in Dell's lineup yet that fits that description yet.
But there's another limitation here. If you have two U2720Q displays connected to a dock and they're both running at 60 Hz, then you very likely have a ThinkPad Thunderbolt dock, not a ThinkPad USB-C dock -- unless you have the ThinkPad Hybrid dock, which relies on "indirect display" technology called DisplayLink -- not to be confused with DisplayPort. But either way, you won't be able to run a third 4K 60 Hz display from the dock. With the Thunderbolt dock, you simply don't have the video bandwidth available, because triple 4K 60 Hz displays would require more bandwidth than is available over Thunderbolt 3 or 4, before even considering bandwidth you'd want to use for any non-display traffic to and from the dock. In theory if you had a setup that supported DisplayPort DSC, you could achieve this, but I haven't seen laptop, dock, and display setups in the wild that run that yet. And if you instead have the Hybrid dock, then the DisplayLink chipset that it uses only supports dual 4K 60 Hz displays.