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Techbuyer2
Fanfold Paper
Posts: 4
Registered: ‎11-01-2017
Location: US
Views: 5,443
Message 1 of 5

Connect 2 external monitors to Yoga 720 15'' using daisy chaining? (WITHOUT a Dock)

Hello all,

 

As the Yoga 720 15'' has only one Thunderbolt port, with no other ports for connecting more displays, I'm looking for a solution for connecting two monitors through this single port.

 

The problem is that the Thunderbolt 3 to dual DisplayPort adapters do not seem to be working on this laptop for some reason according to threads on this forum. (although it has the appropriate hardware I suppose?)

I saw a solution using the Lenovo Thunderbolt Dock, but it's quite expensive...

 

I thought to myself: suppose I have two monitors that supported DisplayPort daisy chaining, could I use this ability and connect them to the laptop?

 

Connecting one monitor directly to the laptop, and then connecting the other monitor to the first one using daisy chaining. Like so:

Yoga -> Thunderbolt to DispalyPort adapter -> Monitor 1 -> DisplayPort -> Monitor 2. 

 

I couldn't find any info about this method (only that it is possible on the XPS 15 which also has Thunderbot with two lanes only...)

 

 

Have someone already tried this method? Or could try it? (pretty please... Smiley Happy)

Or could at least tell me if it is possible?

 

I'm really looking forward to buying this laptop and this is the main reason that stops me... Smiley Sad

 

Note: I am aware about the bandwith limitations. I plan to use only two 2K displays.

 

Thank you!

chx
Token Ring
Posts: 105
Registered: ‎09-08-2009
Location: CA
Views: 5,404
Message 2 of 5

Re: Connect 2 external monitors to Yoga 720 15'' using daisy chaining? (WITHOUT a Dock)

Daisy chaining for DisplayPort monitors is just a built in MST hub. It's completely different for Thunderbolt. So you can just buy an MST hub yourself and whatever monitors you want, as you rightly note, within the bandwidth of a single connection (4 lanes) DisplayPort 1.2a.

Techbuyer2
Fanfold Paper
Posts: 4
Registered: ‎11-01-2017
Location: US
Views: 5,395
Message 3 of 5

Re: Connect 2 external monitors to Yoga 720 15'' using daisy chaining? (WITHOUT a Dock)

Thank you for your reply and suggestion.

However, in my post I was thinknig about using this product: 

https://plugable.com/products/usbc-dp/

 

It says in the QA section that the adapter supports DisplayPort MST daisy chaining, so you can connect your laptop to a supported display, and then connect a second supported display to the first one.

 

Even in the video they added on that page, it is clearly shown that all of this is possible and working on the Dell XPS 15 (which has, again, a USB type C thunderbolt port with 2 PCI-e lanes as the Yoga 720 has)

https://www.youtube.com/watch?v=Rm9gaIxsKh4

 

I was just wondering if this method is compatible with the Lenovo Yoga 720 15'' laptop as well...

 

Thanks again Smiley Happy

 

EDIT:

Even Lenovo itself has a similar adapter:  Smiley Surprised

https://www3.lenovo.com/us/en/accessories-and-monitors/cables-and-adapters/adapters/CABLE-BO-USB-C-t...

 

From the overview section:

"Features:

This legacy companion creates and easy way to connect USB C enabled systems to connect to DisplayPort enabled monitors and projectors

Connect to multiple DisplayPort connections (daisy chain)"

 

Which again, I dont know if it works with the Yoga 720 specifically :/

chx
Token Ring
Posts: 105
Registered: ‎09-08-2009
Location: CA
Views: 5,390
Message 4 of 5

Re: Connect 2 external monitors to Yoga 720 15'' using daisy chaining? (WITHOUT a Dock)

What you need to understand, and I know this is hard and confusing: if one monitor works then MST works too.

 

What I mean here is that some laptops and most phones do not have a DisplayPort signal routed into the USB C socket and then you can't get a single DisplayPort monitor working. But if one works, then the same signal can carry multiple streams , that's what MST stands for, Multiple Streams Technology. Whether it's a little external box or one of the monitors contains the necessary circuit to pick a stream and feed it to a display doesn't matter.

 

An external MST hub will take a USB C or DisplayPort input and present you 2-4 DisplayPort outputs.

 

A daisy chaining monitor will have a hub like that inside with one of the outputs hardwired into the display itself, the other presented for chaining.

 

What I also meant is that the daisychaining happens via Thunderbolt (which of course is confusing since the physical plug is the same!) then everything is very different and I simply won't go there today as a low resolution monitor won't use a Thunderbolt connection only. LG 5K Ultrafine use a TB connection, as an example -- but it doesn't chain.

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Flosz
Paper Tape
Posts: 2
Registered: ‎09-04-2017
Location: US
Views: 1,159
Message 5 of 5

Re: Connect 2 external monitors to Yoga 720 15'' using daisy chaining? (WITHOUT a Dock)

I just figured out that Lenovo Yoga 720 15IKB thunderbolt C can only support 1 external HDMI (as shown in the table here:  https://plugable.com/products/tbt3-hdmi2x-83/   ) which is a deal breaker. I got around it by using 1 thunderbolt C to HDMI to direct the signal to my main monitor. I then also bought a USB 3 extender so I get 4 more ports. I can then use 1 of it to connect to my other monitor using USB3 to HDMI converter. Everything is working fine for me now.

 

It would be better if they just allow 2 video output to harness the whole power of this laptop and its thunderbolt C but for some reason they didn't. However, my solution works good enough for me so I guess it's OK.

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