[SOLVED] Monitor working for one computer but not the other

[Grace Wong]

Hi, I have a bit of a weird problem that my post title doesn't do justice... I'll try to keep this relatively short...

I have a client with two older computers - one was a Dell that came preinstalled with Windows 8 and an Acer that came preinstalled with Windows 7. Both are now running Windows 10. They never ran in tandem. Everything is onboard both (ie. no GPUs on either one). The Dell supports VGA, HDMI and DP; the Acer supports VGA and HDMI.

He used a simple 22" LCD monitor.

Recently, he purchased an HP Envy 34" curved screen monitor that supports HDMI, DP and USB-C. He only has two HDMI cables. When he purchased said new monitor, he plugged it into the Acer (which he is calling his "new" computer - ie. it's the one he wants to use right now). There's no picture on the monitor. That's when he called me in. So I did the standard troubleshooting (using both HDMI cables) and here are the results I got:

Dell plugged in via VGA to 22" monitor - works
Acer plugged in via VGA to 22" monitor - works
Dell plugged in via HDMI to 22" monitor - works
Acer plugged in via HDMI to 22" monitor - works
Dell pluggeed in via HDMI to 34" monitor - works
Acer plugged in via HDMI to 34" monitor - doesn't work

After much banging of head, I decided to get a little creative and tried setting up the Acer as a dual monitor setup - VGA to the 22" and HDMI to the 34" - and voila - it worked! The Windows settings had the 22" as the primary monitor so I switched it around so the 34" is the primary monitor. I then unplugged the 22" and the 34" monitor stayed on and I figured that was it; everything was solved.

Nope.

When I rebooted, the 34" stayed black. So I plugged back in the 22" and it was also black. So I rebooted yet again and the computer wouldn't even POST (I'd turned on the verbose setting of the BIOS so I could see everything happening during POST) - I'd get a blinking cursor on the 22", the screen would go black and then the blinking cursor would show up again and stay there. I tried this a couple more times and same thing happened. So I unplugged the 34", left the 22" plugged in and Windows booted up just fine. WTH? I plugged back in the 34" and the desktop popped up again. So I did the exact same thing I did the first time - rebooted and the exact same thing happened. So essentially, he can't reboot his computer or he loses the ability to boot into Windows. He doesn't want a dual monitor setup (small desk space), but when I left his place a couple of days ago, it was temporarily setup as dual, with instructions to NOT reboot his computer until I was able to come back again.

So that's where we stand right now. I'm hitting up the computer store later to pick up an HDMI to DP adapter cable and an HDMI to DP adapter. I'll be trying them when I go back tomorrow. However, on the off chance this simple fix doesn't work, does anyone have any insight as to what might be causing the problem and how to solve it or at least make it workable so his computer can reboot occasionally?

Thanks muchly...

 

[Ralston18]

Try Powershell and specifically the cmdlet:

Get-WmiObject win32_VideoController

Run the cmdlet in each of the above configuration and combinations that you have tried include single and dual monitors.

First just look at the display outputs to determine what may be different being displaying and not displaying by comparing the cmdlet results.

You can make the comparisons easier by send the output to a printer by piping with Out-Printer.

Get-WmiObject win32_VideoController | Out-Printer

(My printed results were 2 1/2 pages each.)

My thought is to start by comparing

Dell plugged in via HDMI to 34" monitor - works
Acer plugged in via HDMI to 34" monitor - doesn't work

Look for some difference in the Dell versus Acer results.

Or Acer 22" compared to Acer 34"

Reference:

https://winbuzzer.com/2020/08/21/how-to-check-what-graphics-card-you-have-on-windows-10-xcxwbt/

(Step 6. Recommend that you read through the entire article beforehand.)