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  • Registered: ‎11-17-2017
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X1 Carbon 5th Gen (20HR) + Thunderbolt dock

2017-11-17, 23:05 PM

I recently purchased the X1 CRBON 5TH Gen (2017)...type 20HR plus a thunderbolt dock.

I connected them together with a Dell 28" 4K (@30Hz) screen (p2815q) connected through DisplayPort from the dock, plus a Microsoft keyboard and Jabra 510 USB speakerphone.

Using the Windows 10 stock image from Lenovo, plus Office 2016, Chrome, Visual Studio, Skype,  and various other apps (putty, RDP, SAP GUI, others) the video performance was atrociously bad. Alt-Tab, which I use heavily would take 3-4 seconds to respond, switching between applications, Windows would freeze and sometimes crash, I would often get blank or black windows in Chrome and Office. This was on the embedded Thinkpad screen as well as the external monitor.

I ensured Windows Update was up to date, as well as Bios, Drivers etc through the Lenovo companion app.


So...I dove into the BIOS and voila! There is a switch that lets me change the Video memory from 256 to 512 MB allocated!

I went to change it, and it would not change until I changed the setting:

BIOS > Config Thunderbolt 3 > 

  • Security Level = from "User Authority" to "DisplayPort and USB"

I switched that setting, and then set my video memory to 512 MB, rebooted and voila! Problem solved.


I worked that way for a little while, took it into my office and plugged it back into my Thunderbolt 3 dock and while my video and LAN connections worked...my wireless keyboard (USB dongle), and Jabra 510 did not. Curious.


I reached out to support, had some trouble getting to someone who could answer my question (bounced between X1 Carbon and Thunderbolt Dock support on the hardware side, and over to software support and back again.) 

I tweeted to Lenovo and they pointed me in a Direct Message to this article:



That article walks you through setting all the settings back to default, including the Video Memory back to 256 MB.


I am back there right now, with poor video performance and crashing apps. Help please...!?!


Is there no way I can have a properly performing video card AND use USB accessories through my Thunderbolt dock?


It doesn't make much sense having a dock if I cannot use USB accessories with it...?



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Re: X1 Carbon 5th Gen (20HR) + Thunderbolt dock

2018-01-17, 1:54 AM

Come on LENOVO.  Give us an answer!  Does the Thunderbolt 3 Dock WORK AS PROMISED with 512MB video memory?  My Carbon X1  + TB3 Dock were almost $2,500 - they HAVE to work as promised!


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  • Registered: ‎04-06-2018
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Problems X1 Carbon 5th Gen (20HR) + Thunderbolt dock - losing connectivity via the dock

2018-04-06, 8:43 AM

I have had continuously problems with my Thunderbolt C dock. First I lose ethernet connection via the dock. Then other attached hw lose the connection. I have had my Thunderbolt C dock replaced already 3 times. Is there something I do wrong with the dock, or is it just bad product quality?


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Re: Problems X1 Carbon 5th Gen (20HR) + Thunderbolt dock - losing connectivity via the dock

2018-04-09, 9:09 AM

I have issues as well. When the laptop (X1 carbon 5th gen) is disconnected from the dock and reconnected again, often the dock does not recognize the keyboard anymore, or indeed loses ethernet connectivity. A reboot is required to get them working again.


I also have an issue with the video driver going nuts when the laptop wakes up from sleeping mode (all kinds of crazy patterns on the attached screens until the dock is powercycled).


This, together with the random screen blanking and lockingof the X1 carbon makes using these Lenovo products and exercise in extreme frustration.

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