4 external monitors on T420s?

I have searched the forums and gathered some great information about how folks have added multiple monitors to their systems, but I did not find an answer to my question.

I recently purchased a Lenovo ThinkPad T420s (4171-6JU) with dedicated 1GB NVIDIA N12P-NS2 graphics after reading about support for quad monitor setups using the Advanced ThinkPad Mini Dock Plus Series 3 (4338-10U), which I also purchased. I have three external monitors running(Hanns-G HH251 with 1 of 2 Dell P2210H's in portrait mode on either side) running, plus the native laptop display in a laptop stand at work, and I am happy to say that everything works as advertised. For my home setup, I typically keep the laptop & docking station out of site in a desk cabinet with the lid closed and have a triple monitor setup on my desk. This works fine also.

My question is whether or not the onboard graphics are capable of running a fourth external monitor, since the card is not being used to drive the native laptop display when the lid is closed? There is nothing published by Lenovo to say that this can work, but I am wondering if there is some setting or BIOS tweak that would enable this functionality.

If anyone can answer my question, I would greatly appreciate it.

Other details:
i7-2620M(2.70GHz), 4GB RAM, 160GB Solid State Drive, 14in 1600x900 LCD, 1GB NVIDIA N12P-NS2, Win7 Pro 64

 

Yes it can u need to use the dp port on the laptop itself to drive the fourth monitor. Alternatively get a usb2dvi and u can drive 5 monitors.

 

I used a Startech DP->DVI adapter for the 4th LCD panel with mine.

 

Thank you for the fast response, and the good news. This is interesting because I expected that being docked would prevent either the onboard displayport from working. I already tried running a monitor from the onboard VGA port while the laptop was docked, and it did not work. This was the case even when I disconnected the monitor that is currently attached to the VGA port on the docking station. I have displayport cables being delivered to me this week and will test to confirm that it works.

Also, thanks for the suggestion about the USB2DVI adapter. I actually tried that solution with a previous computer using a high performance adapter from Tritton Technologies and experienced significant lag. The lag was even noticeable during simple tasks like web surfing. If I need a 5th monitor, I will probably go with the V-dock that a few folks on the forum have mentioned.

 

the lag issue will be present to some degree due to the limited bandwidth of the usb 2.0

 

Is it possible to use 2 external monitors + the internal display on an X220 with MiniDock 3?

 

not without the usb 2 dvi converter.

 

Yes, but hopefully this will all change in the months ahead thanks to DisplayLink's planned additions to the product line...
AnandTech - DisplayLink Shows Off USB 3.0 Video Adapters

 

So, I tried connecting a 4th external monitor to the laptop dp port and it did not work.

There is recognition by the system that the 4th external monitor is connected, but it won't allow me to enable all 4 at once with the laptop lid closed as I expected. When I open the lid, the 3 external & laptop monitor all function.

I checked the NVIDIA control panel and it states that the NVS 4200M can drive up to 2 displays. The third monitor is currently being driven by the Intel HD Graphics Family, but it will not allow me to drive a fourth external monitor. Since the lid is closed, and the laptop monitor is not being used, I thought that I would be able to drive 2 external monitors using the onboard Intel graphics. My 4 year old Dell drives 2 external monitors when I close the lid, so I thought this would work on my new 420s.

Is there a setting that I need to change that will allow the 4th monitor to be an external one vs. the laptop screen?

 

Which three connectors are you using on the dock?

For the 4th monitor, is the connection DisplayPort on both ends?

Are you using the video drivers at NVIDIA NVS 4200M, Quadro 1000M, Quadro 2000M (Optimus) Display Driver for Windows 7 (64-bit) - ThinkPad

What BIOS are you on?

 

BIOS Version/Date: LENOVO 8CET46WW (1.26 ), 7/11/2011
SMBIOS Version: 2.6

 

I tried it using the following configurations:
1)VGA port & 2 DisplayPorts on dock & laptop DisplayPort
1)VGA port, 1 DVI, 1 DisplayPort on dock & laptop DisplayPort

Right now, I have the 3 externals hooked up using a DisplayPort to HDMI female adapter running a HDMI cable to the HDMI input on my Vizio 322VL for DisplayPort output #1 on the dock, DVI output for 2nd monitor, and VGA for 3rd with nothing hooked up to the output on the laptop. I can use any combination of connections or adapters necessary to make it work. My only limitation is that the Vizio (main center monitor) only has VGA or HDMI inputs and the same holds true for my Hans G HH251 which will be the 4th monitor. My other 2 monitors are Dell P2210H which have the option of hooking up via VGA, DVI, or DisplayPort.

I have tried multiple configurations:
1)using DisplayPort on both ends
2)using a DisplayPort to DVI adapter
3)using a DispayPort to HDMI adapter
and none have worked

No, I was not, but downloaded and installed them after receiving this response. Thanks for the heads up. Unfortunately, after just trying multiple configs again there is no change.

Updated after reading your response to the latest BIOS.
Now have LENOVO 8CET48WW (1.28 ), 8/15/2011

 

Bummer.

When I did my testing, I used the two DVI ports on the dock, the VGA port on the dock, and the DisplayPort adaptor on the T420s. The Display port connection was actually DP->DVI using the Startech adapter at DisplayPort to DVI Video Adapter Converter

It worked pretty much as expected using the display properties in Windows 7 Ultimate x64. I didn't need to resort to the Intel or NVIDIA control panels.

I'm not sure what to tell you at this point. It appears the biggest difference in the two implementations are the monitors. I used standard Dell LCD panels across the board with DVI and VGA connections.