Mini Dock Plus Series 3 with Triple Monitors

[rutledge]

Hi,

I have a T420 with the Optimus graphics card, a Mini Dock Plus Series 3 170W, and two DVI monitors. I would like to use both monitors as well as the screen on my laptop, all at once.

The guide page for the dock says that, for three monitors, you need: "any combination of the following..." and lists the ports. But, this description is ambiguous as to whether you can use two DVI ports at once, or whether you can only use one of each of the ports.

When I plug in both monitors and open my laptop, one of the monitors shuts off. Do you guys have any suggestions as to how I can set it up?

[solar]

Have you checked this site?

http://support.lenovo.com/en_US/research/hints-or-tips/detail.page?&LegacyDocID=MIGR-76617

And do you have Optimus enabled in the system?

I guess you have checked what are Windows showing in Monitor/Display setup.

[rutledge]

Hi, thanks for your response.

I did go there, and I saw:

2nd and 3rd Displays: Any combination of the following:

• DisplayPort on ThinkPad
• DisplayPort on Mini Dock
• DVI digital port on Mini Dock
• VGA analog port on Mini Dock

Which is ambiguous as to whether you can have 2 DVI monitors at once.

My impression was that different applications did or did not use optimus, and it was detected automagically. How can I "enable" Optimus?

[lead_org Microsoft MVP Contributor · Accepted solution]

you need to run the third monitor from the vga port on the dock or the displayport from the laptop itself.

[rutledge]

I wonder: Why can you not use two DVI ports in addition to the laptop monitor? Are there two DVI ports solely for the purpose of using them when the laptop is closed?

[lead_org Microsoft MVP Contributor]

@rutledge, you can use two dvi ports in addition to the laptop monitor, provided you have the Optimus technology.

[rutledge]

Hi lead_org,

I have an Optimus graphics card, and I cannot use two dvi monitors in addition to my laptop monitor. Two monitors work fine when the laptop is closed. If I dock it open, or open it when it's docked, one of the monitors shuts off.

[lead_org Microsoft MVP Contributor]

which laptop model do you have?

is your optimus graphics active?

[rutledge]

I have a T420; 4177-CTO. I don't know how to manually enable Optimus. As far as I can tell, the point of Optimus is that you don't turn it on by hand. Do you know how to mess around with that?