X1 Carbon with 3 displays

[BigFick]

I have a new X1 Carbon with a ThinkPad USB-C Dock Gen 2(PN 40AS0090US) docking station. I have 3 displays connected 2 DPI and 1 HDMI. My 3rd DPI display is running at really low resolution and I can't find how to fix it. Any help will be greatly appreciated.

 

[jeremyshaw]

From the support site,
https://support.lenovo.com/us/en/solutions/acc500106

The User Guide on page 7 (or 11, depending on how you're counting) lists the following warning for Displayport 1.2 devices:
Note: Do not connect three external displays to the dock, because the display resolution is low.

Intel's IGP is extremely dated, and only supports DP 1.2, which simply doesn't have the bandwidth for most dock's lane allocations. There is finally a newer version of Intel's IGP, but it's lacking a few key business features, so it will not make an appearance in business laptops. The other link they show, lists a few "Intel platform" with DP 1.4 - all of those listed are actually driven by an onboard Nvidia GPU.

Here is the master Lenovo list, anyways:
https://support.lenovo.com/us/zh/solutions/pd029622#Ultra Docking

As for resolving the problem, I see at least four routes.

1. A decent Thunderbolt 3 dock - easiest. This thing aggregates 2 DP 1.2 connections (8 lanes total) over the link, and has enough bandwidth.
2. An eGPU TB3 dock - drive the displays with an Nvidia or AMD GPU.
3. The "Ultra" mechanical dock from Lenovo. It uses two USB-C connectors to get the necessary bandwidth, afaik.
4. Use a separate connection for the last monitor. Can you connect 2 monitors via the dock and one via the laptop's other USB-C connector or via the laptop's HDMI?

 

[BigFick]

I read all of the manuals and there are certain configs that allow three displays. I guess mine does not! However, your suggestion , Jeremy Shaw, to connect my 3rd display directly to the laptop worked! I am all set! Thank you!