I must admit that I have little hope for the quick and perfect solution, but I will give it a try.
I just bought an Acer Aspire V Nitro Black Edition VN7-792G with Windows 10 and an external monitor for it, a Samsung LS32D850, and connected both with the HDMI cable that came with the monitor.
It worked extremely well. However, when the laptop switches off the monitor for any reason, like a reboot or an energy saving setting, then the monitor stays black.
I have tried many things, but the only ones that work seem to be these:
Even disconnecting the monitor's power cord for a minute is not enough to make the laptop send an HDMI signal to the monitor.
All other attempts to wake up the monitor yield only spotty or no results, like switching the monitor configuration in Windows (Windows key + P or the equivalent Fn + F5). I can always activate the laptop's built-in display that way, but not the external monitor. I also tried changing the monitor input from HDMI to Auto and back, and various other actions, to no avail.
I checked the Windows Intel video driver, which turned out to be up to date.
I changed to another HDMI cable—same problem.
I have not yet tried to switch to the NVidia graphics adapter, because I'm not sure how to do that. If I could wake up the monitor that way, I could then switch back to the integrated Intel graphics, which I almost always use, and that might be a viable workaround while waiting for the defect to be repaired, perhaps in the video driver.
I have upgraded Windows 10 from Home to Professional, which made no difference to this problem.
Any ideas are welcome. I am pondering the thought of returning the monitor, but (a) I like it, and (b) it is quite possible that the defect is in the laptop and the next monitor would have the same problem. At first sight it is the laptop that causes the problem, because it is obviously not sending HDMI output to the monitor.
I am also pondering the thought of adding an HDMI switch to allow me to wake up the monitor by switching the HDMI line. For that I would have to identify and buy a pure HDMI pass-through switch, which I find difficult so far. It would be a stupid solution though.
I read that this is a widespread and long-lived problem. Intel has an ongoing discussion thread about it that has been running for several years, but no solution.
Any ideas are welcome.
A related question: I would like to try the DisplayPort output, hoping that it works better than HDMI, but that would occupy the USB-C socket, which I plan to use for other purposes. Is it possible to use that connector for multiple purposes at the same time? Is there a special external hub for that?