i have two external monitors connected to my Dell N7520 Notebook, one though the HDMI port, and the other from the VGA one. when they are connected separately, each monitor working as great as it should!
Problem is popping when the VGA port is connected same time with the HDMI. when i do that, Only the VGA monitor is working and the HDMI one is black screened.
when trying to apply "extend desktop to this display" to the HDMI one, i get: The display settings could not be saved. Please try a different combination of the display settings
e.g: when HDMI is connected and working perfectly, trying to connect the VGA one making the HDMI black screened, and the VGA to be working instead..
heres are the specs:
42 Answers
The comments to your answer are pretty much spot on. It's hard telling without actually looking at it, but I have a hunch that the VGA port runs off of Intel HD on-board graphics, and the HDMI port runs off of the 7730M dedicated card.
The reason it works when you use one at a time is because the laptop switches to using the on-board graphics, or the dedicated graphics card. When you plug in both the laptop can only run the on-board graphics, or the dedicated graphics.
This seems to be what is going on. You could probably test this out by plugging both monitors in, then removing the VGA from cable from your laptop and see if the HDMI monitor starts to display normally.
Someone had a similar problem here.
Even if you have both HDMI & VGA outputs, you'll only be able to use one at a time. Or, at best, they will share the same picture output.
You will have to use a USB monitor adapter instead.
