In this mode, your monitor may not receive a full resolution video signal if your laptop graphics card is not powerful enough to deliver the full resolution to both displays.

As it stands, you have to connect your monitor from the 15pin or BNC port on the back to your vid card's output (usually 15pin in PC land). Quote Report ...

We're having a look at how to connect a monitor to the ASUS ROG Ally. This would mean you could play on a larger screen.

Connecting a larger external monitor to your laptop can more than double your screen size, as well as let you multitask like a pro. Here's how to make it happen.