3rd display: laptop and 2 displays

Question

Now my desktop extended to 2 monitors: laptop and display connected to laptop via hmdi.

I decided to add the 3rd monitor and connected it via d-sub to laptop.

Windows 7 detectes it in Control Panel\Appearance and Personalization\Display\Screen Resolution.

I select the 3rd monitor and choose Extend desktop to this dislplay. Click Apply, Save Changes. But Multiple displays field revert itselft to Disconnect this display. And there is nothing on the 3rd monitor.

My laptop video card is Intel(R) HD Graphics 4000. 3rd monitor model BenQ FP71G+. Lapton model name is samsung NP300E5X-A07RU Operating system: windows 7 ultimate x64

Seemingly it's possible with my video card, but question is how to do it?

Answer 1

According to the HD Graphics 4000 triple monitor support page,

In most cases, three independent displays are supported in the following configurations:

• If two of the displays are DisplayPort monitors
• If one of the displays is an Intel® Wireless Display (Intel® WiDi)
• If the built-in display is an Embedded DisplayPort (eDP)

Since you don't have any DisplayPort outputs on your machine, the setup you want only works if your internal monitor is connected via eDP, not LVDS.

To check if your computer's built-in display uses an embedded DisplayPort (eDP) or LVDS connector type: From the Windows desktop, press Ctrl+Alt+F12 key combination. If prompted select Advanced Mode application mode. Select Options and Support, change System Information to Built-in Display. Check the Connector Type field.

If it turns out to be LVDS, this setup is unfortunately not compatible with your hardware.

Note that, as far as I know, the vast majority of current laptops don't use eDP as it's a new standard (except some 3D laptops), so it generally isn't possible to run 3 monitors off an HD 4000 GPU unless your laptop has DisplayPort. (Or if you run one monitor off WiDi.)