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2 Posts

04-16-2021

Denmark

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Dual 4K monitors @60Hz not working with T470S and ThinkPad TBT3 Dock Gen2

2021-04-16, 20:33 PM

I cannot get the ThinkPad Thunderbolt 3 Workstation Dock Gen 2 running 2 4K monitors at 60Hz. Only 30Hz was working.

 

Computer:

Lenovo T470S (20HF) - Thunderbolt 3 enabled

 

Docking Station :

ThinkPad Thunderbolt 3 Workstation Dock Gen 2 – 40ANY230EU

 

Screens:

2 x BenQ PD2700U 4K @ 60 Hz

 

All drivers and firmwares are updated to the newest version.

Cables used for connecting are DP1.4 compatible (Should be able to run 8K).

Thunderbolt 3 cabled is used to connect the computer to the dock (>0.5 meters)

 

The following was tried without getting 60Hz on both screens.

 

Connecting Screen 1 to DP1 and Screen 2 to DP2:

2 x 4K @ 30Hz

 

Daisy changing Screen 1 to Screen 2 and connecting in DP1:

2 x 4K @ 30Hz

 

Connecting Screen 1 to DP1 and Screen 2 to USB-C on front of Dock:

1 x 4K @ 60 Hz

The other screen is not responding. However, when unplugging the working screen (DP1) the other screen turns on (USB-C). However, when reconnecting the second screen to DP1, only USB-C has signal. Disconnecting USB-C while this signal is working, will cause the screen on DP1 to get signal.

So at the moment I can only get signal on 1 Screen by connecting to USB-C / DP1. This should however be possible according to the specification.

 

It took me a while to figure out that you could not use DP1 and DP2 to get 2 x 4K@60Hz, as one of the screen must be connected through USB-C while the other could be DP1/2. This is however not working…

 

I have also tried connecting a newer ThinkPad T14s Gen 1 without any changes to the result.

 

Any help or ideas would be appreciated.

 

Cheers

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3591 Posts

08-02-2018

United States of America

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Re:Dual 4K monitors @60Hz not working with T470S and ThinkPad TBT3 Dock Gen2

2021-04-16, 22:08 PM

Hello DSDK1234!

 

Welcome to community forums

 

The Thinkpad T470S can only have two maximum external monitors via USB Type-C(4096 x 2304 @ 60Hz) and HDMI(4096 x 2160 @ 24Hz) and you can refer to the product reference here: https://psref.lenovo.com/Product/ThinkPad/ThinkPad_T470s

 

Here is also a guide on the dock setup: https://support.lenovo.com/ph/en/solutions/pd029622-display-and-video-output-configurations-docking-stations#Thunderbolt%203%20Workstation%20Dock%20Gen%202

 


Jwes_Lenovo



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304 Posts

09-04-2019

United States of America

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Re:Dual 4K monitors @60Hz not working with T470S and ThinkPad TBT3 Dock Gen2

2021-04-17, 7:38 AM

The ANY was pulled from the market from what I read and replaced by the ANO version of the dock. This is what I read on AMZN. Maybe that is the issue.

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572 Posts

06-26-2016

Germany

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Re:Dual 4K monitors @60Hz not working with T470S and ThinkPad TBT3 Dock Gen2

2021-04-19, 12:32 PM

@ DSDK1234 wrote:

 

Lenovo T470S (20HF) - Thunderbolt 3 enabled

I have also tried connecting a newer ThinkPad T14s Gen 1 without any changes to the result.

Any help or ideas would be appreciated.

 

as you have already shown,  your systems do not support dual 4K screens at 60Hz.

The Thunderbolt controller in those systems (only one Thunderbolt compatible USB-C port)  do not support 2 DP1.2 channels like the Carbon, or Yoga systems do.

The new ThinkPad T14/5  Gen 2 Intel systems support DP1.4.

 

take a look at this document

 

Tech-Savvyness does not replace reading the fine manual.
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2 Posts

04-16-2021

Denmark

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Re:Dual 4K monitors @60Hz not working with T470S and ThinkPad TBT3 Dock Gen2

2021-04-19, 14:32 PM

Thanks for the replies.

 

I was not aware the thunderbolt 3 controller was dependent on the machine.

I understand now that only 2x 4K @ 30 Hz is achievable.

And from what I understand it would not make a difference using another docking station like the CalDigit Puls, as the limitations are in the computer not the docking station.

 

I still think the limitations of the thunderbolt controller are weird, as it still runs 40Gbps. But then again it is more complicated that so.

 

From my perspective it is very difficult to figure out the limitation of the Docking Station from the support site. I thought that running 1 screen to TBT Dock DP1 and another screen to TBT Dock USB-C, would solve the issue, but that only works for X1/yoga I see.

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