Q: Current Dock, 2 digital displays at the same time?

[MortySE]

Dear all,

First post....

I just had an unhelpful chat with Lenovo. My question concerns the currently shipping Thinkpad Pro Dock (# 40A10090US / 40A10090EU) and external displays.

Lenovo's description of this dock says something I don't understand:
"1x DisplayPort 1.2 (Exclusive use with DVI-D)
1x DVI-D (Exclusive use with DisplayPort)"

What does the "exclusive use" thing mean? Lenovo was unable to explain this.

What I would like to do is:

• Drive an external monitor at 1440 × 900 as primary monitor (built-in screen disabled), over DVI-D.
• At the same time, drive an external TV at 1920 x 1080 over the Displayport connector, via a Displayport-to-HDMI cable, as secondary monitor for media playback.

Will this work? Or does "exclusive use" mean those two connectors cannot be used at the same time, only one or the other can be used?

The computer is a Thinkpad T440p with Intel HD graphics.

Thank you very much!

[dr_st]

Welcome to the forum.

If my memory is not deceiving me, then, yes, unfortunately for you, it means that DVI-D and DP cannot be used at the same time on the Pro Dock. You'd have to get the Ultra Dock to get two simultaneous digital displays.

This was one of the biggest complains about the new docks. With the previous, even the basic Mini-Dock Series 3, imposed no limits and allowed two digital displays to be used at the same time.

[MortySE]

@dr_st: Thank you very much for your kind greeting.

means that DVI-D and DP cannot be used at the same time on the Pro Dock.

Sic. That would be the exact opposite of what Lenovo's sales just told me -- in that unhelpful chat I mentioned. (They did answer me, but the answer seemed so inept that I chose to doublecheck.)

[MortySE]

I can confirm that this dock does not allow both digital screen outputs to operate at the same time.

Then I have a new question: Is there a way to switch which digital output will be used via a shortcut key or similar? I.e. change from using DVI-D to using Displayport and vice versa?

Thanks

[dr_st]

What happens when both inputs are occupied at the same time? Does the OS detect both displays but only outputs to one? Or does it detect only one?

[MortySE]

What happens when both inputs are occupied at the same time? Does the OS detect both displays but only outputs to one? Or does it detect only one?

There are 3 displays, the built-in, a monitor on DVI on the dock, and a TV on Displayport on the dock. I boot the PC up with the lid closed.

After boot Windows 10 lists two displays: The built-in display, and the external TV (which is connected to the Displayport connector on the dock).

I couldn't get it to select the other interface, the DVI. That one seemed completely off, and the connected monitor reported no signal.

[dr_st]

Well, that does not look too promising then, in regards to the ability to switch the active output in software.

It appears that the dock prefers DisplayPort and turns DVI off when DisplayPort is connected.

What happens if you plug a dead DP cable to the DisplayPort out (i.e., a cable connected to nothing at the other end)? Does DVI become available then?