External Monitor periodically displays a black screen but is still connected

Dec 18, 2018
Context: I'm pretty sure I've narrowed this down to it not being a defect in the monitor after trying it on another computer. The monitor (Lenovo, 1440p 60hz) is connected to my laptop (ASUS 1080p 60hz) running Intel HD 520 and discrete Nvidia GTX 960M, via HDMI. Both GPUs support up to 4k.

The monitor is 2 weeks old and had the problem right out of the box. My laptop is 2.5 years old but has never had any issues.

Problem: External monitor flashes black for about 2 seconds, every 5-30 minutes or so. My computer still detects the monitor, so HDMI connection remains. Sometimes when it goes black, it won't return to normal and the only thing that temporarily fixes it is to reconnect the HDMI cable. My laptop's built-in monitor isn't affected.

What I've Tried:

    Updating BIOS
    Updating all display drivers & Windows builds
    Restoring Nvidia driver to ASUS manufacturer default
    Using a different computer, HDMI cable, and wall outlet

Assumptions: I'm guessing the issue has to do with my laptop's integrated Intel GPU, since I have no choice but to connect to that while using a laptop.

I thought this would be easier to solve since I'm studying this field, but it's leaving me stumped. Any input is largely appreciated.