[T430s] HD4000 + dock 4337 can't display triple monitors

[whqdz]

Hello

I'm trying to connect 2 monitors to my dock (displayport + vga) with a t430s but no success, I can't display both at the same time (+ built-in). The laptop doesn't have nvidia discrete GPU.

It looks like it's only possible to display two monitors, even if intel hd 4000 can support up to three monitors.

Does anybody know if there is a way to fix this?

Thank you.

[dr_st]

Strange. DisplayPort + VGA + Internal should work.

Which OS? Which driver? Maybe it needs to be updated?

[whqdz]

I tried different combinations while both screens are connected to the dock :

- built-in + DisplayPort : OK
- Built-in + VGA : OK
- DisplayPort + VGA : KO
- Built-in + DisplayPort + VGA = KO
- Only DisplayPort : OK
- Only VGA : OK
- Only built-in : OK

Software side:
- I'm running Arch 2019.05.02, I also tried from a Ubuntu 18.04 live cd but still facing the same issue.
- I installed dockd and re-installed acpi in order to try, no success.
- xrandr doesn't want to display 3 monitors at the same time.
- Tried the same with arandr

The VGA (or DisplayPort, depends which one I use as second) stays with "no-signal". What is very weird is that "xrandr" output shows the two external minitors with their framerate and resolutions, but the laptop can't handle signal to both at the same time.

[Whitieiii]

No it can only handle
vga+internal or
displayport+internal or displayport+displayport+internal (via docking station) on Intel graphics machines

Just need the dock with 2 displayports to be able to output to two monitors and the built in screen at the same time....

Sent from my BBF100-2 using Tapatalk

[dr_st]

The exact limitation is that 2 of the 3 displays must be DP displays, because there are only 2 PLLs in the chipset, and only DP displays can share a PLL.

A small exception is that if the two external monitors are exactly the same resolution and refresh rate, then you can get it to work even if one (or both) of them is DVI, however I could never get it to work under Windows, only Linux. And I never tried DP+VGA+internal.

More info here:
viewtopic.php?t=123257#p797092

[whqdz]

Thank you really much Whitieiii and dr_st. I've seen a post where the OP was talking about 2x DP or 1x passive DP + DVI but I was not able to find it again. You gave me all informations I needed

I'm gonna give a try to a passive DP++ to DVI dongle on the 4337 Dock and once the work has been done I'll keep some news here.

Thank you again