I have an Dell XPS 15. To extend the display, I have a Dell P2214H Monitor. I have also used multiple cables in multiple configurations to use an extended monitor, including (DP means DisplayPort):
Laptop Mini DP > MiniDP To DVI Adapter > Monitor DVI (Current Setup)
Laptop Mini DP > MiniDP To DP Adapter > Monitor DP
Laptop HDMI > Monitor DP (obviously fail)
Laptop HDMI > HDMI To DVI Adapter > DVI
Laptop USB3 > USB3 "Dock", Dock's DVI > DVI
Laptop USB3 > USB3 "Dock", Dock's DVI > DVI To DSub Adapter > Monitor DSub
Laptop USB3 > USB3 "Dock", Dock's HDMI > Monitor DP (obviously fail)
Laptop USB3 > USB3 "Dock", Dock's HDMI > HDMI To DVI Adapter > DVI
I have also used different monitors, I have a bunch of the same model. So the monitor is not to blame per se. I have a Windows 8 computer (Dell Optiplex 9020) with the same monitor model sitting next to the laptop's extended monitor.
On the laptop: in the included Intel HD Graphics Control Panel, I can only alter settings of an extended multiple display setup if the monitor is interfacing with the Laptop's HDMI or Mini DP Ports. The Intel HD Graphics Control Panel does not recognize a second monitor if I go through the USB 3 "Dock."
The NVidia GeForce Control Panel only has settings for 3D Settings for gaming, nothing else that I'm used to seeing.
Also, I downloaded DELL_P2214H-MONITOR_A00-00_DRVR_HXFX0.exe to my desktop from dell.com/support/home/us/en/19/Drivers/DriversDetails?driverId=HXFX0 and unzipped it to c:\Dell\Drivers, and installed it by running "c:\Dell\Drivers\HXFX0\Dell Monitor Driver Installer.exe"
I also tried pulling the monitor power to try to reset it... and maybe a few other weird things I'm not thinking of.
My problem is this:
On the laptop, when I open the basic windows "Screen Resolution" control panel, my Resolution is set to 1920 x 1080. Beneath the resolution selector, a message reads, "Your resolution is lower than 1920 x 1440. Some items might not fit on your screen."
I don't really care about that message. But my Recycle Bin and other desktop icons are HUGE. Also, the Task-Bar is larger than normal. Also, Internet Explorer and Lync, just to name a couple, appear like I have 800x600 resolution. It's horrible.
Chrome, Microsoft Outlook, and many other applications appear to be showing in 1920 x 1080 resolution as I'd expect. However, when I drag from the laptop to the extended monitor, they are first HUGE also, but they appear to re-scale themselves after a second to seem correct.
So it seems like the Laptop's extended monitor is stuck at a lower resolution, but some applications re-scale or something. wtf