Are you willing to send your system to us?
Outside of Germany: No.
Is your system a laptop or desktop?
Laptop
What is the make/model of your system?
Dell XPS 15 (L521x)
What is the model of your CPU?
Intel i7-3632QM (Intel HD 4000)
What is the make/model of your failing display(s)?
Original Dell Laptop Screen + external Monitor HP Z27x
If laptop, is your built-in display failing?
Yes, the internal becomes black (backlight is on) and if I'm choosing "duplicate" through win + p the external monitor looses the signal.
What is your operating system?
Windows 7 Ultimate 64-bit
What display driver version do you have installed?
10.18.10.3621
What type of connection are you using? (HDMI, VGA, DP, DVI?)
- Internal connection (Intel HD 4000) for internal screen
- DP (NVIDIA GeForce GT 640M) for external monitor
What happens that results in the blackscreen failure?
It happens randomly if:
- I'm in "projector only" mode through Win + P and select "extend"
- windows has turned off the displays through the energy settings and I move the mouse to turn it on again
In both cases the external monitor will never become black. Only if I choose "Duplicate" through Win+P the external monitor looses the signal. This is strange as the external monitor is connected to the DP port of the Nvidia GPU. In this situation I'm only able to choose (blind) "extend" again by win + p > 2x right arrow > enter. This will switch on the external monitor again.
What solves the black internal screen issue:
- In 100% of all cases I was able to turn on the screen by turning the Laptop into sleep mode (led is blinking). But since updating the Intel HD 4000 to the recent version and updating the Nvidia driver to the recent version 340.52 (9.18.13.4052) I need in rare cases multiple tries to turn on the screen again by this trick. Unfortunately I don't know which of the updates made the situation even worse.
- turn into hibernation and turn on again
- restart windows
What does not solve the black internal screen issue (it stays black with backlight on):
- changing resolution of internal screen (flashes only)
- switch off internal screen for a longer time through win + p "projector only" (internal screen is turned off completely) and choose "extend" afterwards to turn it on again (internal screen is black)
- start -> "log off" (flashes only)
- disabling the "Intel(R) HD Graphics 4000" through the device manager (screen turns off completely) and enable it again (turns on black again)
- disabling the monitor (nothing happens at all)
- disabling "Intel(R) Display-Audio" (nothing happens at all)
- changing orientation (flashes only)
- re-attaching DP cable (external monitor looses and gains signal as usual, laptop stays black)
- connecting the external monitor through HDMI as well. HDMI runs through the Intel HD 4000 without problems (now having three extended screens), but the laptop display stays black
- connecting hdmi as before: now select "duplicate desktop on 1 and 2". As before HDMI works, but internal laptop screen stays black
- turn off/on windows aero (advanced settings -> performance options -> adjust for best performance)