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RockTheBoat
What's DOS?
Posts: 2
Registered: ‎10-18-2019
Location: US
Views: 293
Message 1 of 5

ThinkPad USB-C Dock Gen 2 - Dual 2K External Monitors

Hello,

I am using a brand new T490 notebook (Type 20N2, 20N3) connected to a ThinkPad USB-C Dock Gen 2 (40AS0090US) dock. Connected to the dock are two 2560 x 1440p 60hz monitors. Both using the DisplayPort connectors of the dock.

 

On one monitor, the resolution is running correctly and at 60hz. On the secondary monitor, the resolution is stuck at 1920 x 1080p at 29hz. All drivers and firmware is updated.

 

This dock supports three external displays with 4K resolutions. Any assistance on why one monitor is stuck at 1080p and not being detected as 2K would be appreciated.

 

Thanks.

aUserHasNoName
802.11n
Posts: 205
Registered: ‎06-26-2016
Location: DE
Views: 270
Message 2 of 5

Re: ThinkPad USB-C Dock Gen 2 - Dual 2K External Monitors


@RockTheBoat wrote:

 This dock supports three external displays with 4K resolutions.


Where did you find this info?  This dock supports 2 monitors at a resolution of 1920x1080@60Hz  if connected to a DP1.2 system like the T490!  With 3 monitors connected the max resolution is just a 1024x768@60Hz.

I guess you are referring to the Thunderbolt3 DockGen2 (40AN). Even this dock do support 3 4k displays only under specific conditions and mostly only at 30Hz.

 

 

 

 

 

 

RockTheBoat
What's DOS?
Posts: 2
Registered: ‎10-18-2019
Location: US
Views: 258
Message 3 of 5

Re: ThinkPad USB-C Dock Gen 2 - Dual 2K External Monitors

Hi,
Dropping the 3 @ 4K claim, I'm only running two external monitors at 2K.

So, according to the spec sheet, I should easily be able to do 3840x2160@30Hz and 3840x2160@30Hz, plus the laptop display, correct?
I'm just looking to do laptop display + 1440p 60hz x2
aUserHasNoName
802.11n
Posts: 205
Registered: ‎06-26-2016
Location: DE
Views: 251
Message 4 of 5

Re: ThinkPad USB-C Dock Gen 2 - Dual 2K External Monitors

 

Which spec sheet did you see to come to this conclusion for two displays? 

 

You have a  ThinkPad USB-C Dock Gen 2(40AS, 40AS0090XX).  The link will open the maximum resolution matrix for your dock.

Then scroll down a bit until you see the 2nd table for DP1.2 systems (your T490 supports DP1.2  not  DP1.4 ).

There you will discover that your dock supports  two connected displays up to a resolution of  1920x1080@60Hz only!

 

 

MrHeidenBerg
Paper Tape
Posts: 3
Registered: ‎11-02-2019
Location: DK
Views: 179
Message 5 of 5

Re: ThinkPad USB-C Dock Gen 2 - Dual 2K External Monitors

I experience the same thing with my T470.

 

Monitor 1 displays 2560x1440

Monitor 2 displays 1920x1080

 

According to this page my T470 20HD is supported: https://support.lenovo.com/us/en/solutions/acc500106

Thereby believing the T470 has DP1.4 and is fully supported!

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