11-19-2019 04:46 AM
I have a T480s with an Intel UHD Graphics 620.
I have connected this to a Dell monitor 2515H and a secondary Dell 2415 using a C-Dock dk1633 40a9.
When use the primary monitor only (2515) i'm able to use the recommended resouton 2560x1440 and the same when I use the secondary (2415) I get the recommendended resolution 1920x1200.
However, when I extend the desktop i don't get the recommended resolution, but another weird 2048x1152 scaled down resolution on the primary screen, the secondary remain on 1920x1200.
This has been working fine until like for some weeks ago, and i have evern reinstsalled the whole computer without luck.
I have updated Windows, Windows GFX Drivers according to Lenovos page, I have upgraded the Computer BIOS, the CDock Bios, Thunderbolt Bios and the Thunderbolt software. I have also tried to create a new custom resolution in the Intel Control panel...
Solved! Go to Solution.
11-19-2019 05:49 AM - edited 11-19-2019 05:49 AM
It seems the usb-c (40a9) dock is not able to drive two displays with more than 1920x1080@60hz. I guess 19201200@60Hz would be also possible. https://support.lenovo.com/de/en/solutions/pd029622#USB-C%20dock
12-09-2019 06:43 AM
I managed to get hold of a Thunderbold 3 Dock gen 2 (Fully updated)(https://support.lenovo.com/de/en/solutions/pd029622#ThinkPad%20Thunderbolt%203%20Dock%20Gen%202)
but I still I cannot use more than 2048x1152 on the primary when extending the desktop, in single display mode this screen han handle 2560x1440
The secondary is showing 1920x1200 as it should in extended desktop mode?
The aspect ratio differ between the screens, is that a problem?
12-10-2019 10:19 AM
Aspect ratio should not be a problem.
Make sure to connect the dock to a thunderbolt capable USB-C port!
I guess the dock should be reported as a thunderbolt device somewhere in the OS.
If dock is connected to a 'simple' USB-C port than the dock will have same resolution restrictions like the other usb-c dock!
12-10-2019 11:35 PM
I'm using the USB-c cable that came with the dock. Drivers and firmaware is updated aswell. The only thing that might be a problem is that I'm using a noname DP cable, but I've tried to replace it with a HDMI with no luck....
The Dock is reported as a Thunderbolt doch, btw...
12-11-2019 06:27 AM
Just to be sure: if you look at the left side of your system, is the dock connected to the 2nd USB-C port from left (the port with the little thunderbolt sign)?
Are both displays connected with DP cables?
Do you use internal display as a 3rd display or is lid closed (just 2 external displays)?
Which display is configured as 'main' desktop?
Could you pls attach screenshots of the display settings dialogs (or intels gfx control panel) for both ext. displays?
12-12-2019 12:02 AM
Somehow, I managed to plug in the dock in the wrong port in the computer (Shame on me). The odd thing is that the dock has been connected to the same port since the beginning. Now I moved the dock to the other port and I had to grant permission to use that firewire port. Everything seems to work now....
Thanks alot for your help!!!!