Solved Why isn't my second monitor detected?

May 24, 2016 at 10:56:46
Specs: Windows 10, i5-6500 / 8 Go of ram
Hello,

Since around a week now, my second monitor has stopped being detected.
Here's how my pc was when it happened :
Windows 10 ( upgraded last summer ( july) from windows 7 -> no issues until last week)
i5 4670K processor
8 Go ram
Z87 G45 motherboard
GTX 770 graphic card
700 W PSU
250 Go SSD
2 To HDD
Main monitor : Samsung SyncMaster S24B350, plugged by vga, with dvi adapter, to the 770
Second monitor : Panasonic TX-L19C20E, plugged by HDMI to the 770

I have access to another computer ( my brother's) to check my hardware for failure, and his computer works fine. I'll call his PC2, and mine PC1
At first, I suspected a hardware malfunction, so I made the following tests and changes :
I tried my GTX770 in PC2, and plugged my monitor 2, with my HDMI cable. This worked fine, I had something on both screens.
I also tried my motherboard + CPU + 770 on PC2. This also work.
I replaced my PSU. with a new one ( 650W)
I replaced my motherboard with a GigaByte H170-HD3
I replaced my CPU with an i5-6500
During all of this, I cleaned my case, replugged everything several times, HDD and SSD moved around.
I also did a clean install of windows 10, using the restauration tool in windows 10 ( not using a cd or flash drive)
I reinstalled my graphic drivers several times, using different versions ( this was one of the first thing I tried), and also trying it with DDU to remove everything.
I tried 2 different HDMI cables, that I confirmed worked anyway using PC2.

Right now, i'm using a GT640 from PC2, that worked fine on PC2, but I still have my problem on PC1, using this other card.

Monitor 1 is plugged to the 640 with a vga cable ( no adapter), and monitor 2 is plugged to the 640 with an HDMI cable.

During boot, only the monitor 1 display POST, and later windows 10 loading. At no point the second monitor display anything.

I tried booting by only plugging monitor 2 with the vga cable, and it displayed POST, and displayed windows 10 loading for a few second before stopping, and then receiving nothing at all. At this point I have to unplug monitor 2 and replug monitor 1 with VGA.

Can anyone think of anything else I can try?
Thank you very much for your time

message edited by calion


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✔ Best Answer
May 25, 2016 at 08:53:39
The Internet tells me your Samsung has an HDMI port. Does the Samsung work if you unplug the HDMI at the Panasonic end, and use it to connect to your Samsung?

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#1
May 24, 2016 at 12:11:26
(Right-click) Start button -> Run -> (type) displayswitch /extend
Does it work now?

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#2
May 24, 2016 at 12:18:10
This doesn't work. Nothing happen. I've tried this with desk.cpl as well, with no luck.

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#3
May 24, 2016 at 14:35:32
Does Windows even see the secondary monitor? I've had problems with Nvidia's HDMI drivers before, where I had to do a clean install of the latest driver, then reinstall over that.

Second question is if you unplug the VGA monitor and reboot, does the HDMI monitor start working?

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Related Solutions

#4
May 24, 2016 at 14:54:01
No, the HDMI monitor is never detected. Windows never see the secondary monitor. I suspected an issue with the HDMI port itself, but it work well on another computer ( PC2). And I have the issue with both the 770 and the 640. The second monitor itself is fine, when tested on the other computer.

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#5
May 25, 2016 at 08:53:39
✔ Best Answer
The Internet tells me your Samsung has an HDMI port. Does the Samsung work if you unplug the HDMI at the Panasonic end, and use it to connect to your Samsung?

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#6
May 25, 2016 at 09:46:30
There is some progress ! With only the first monitor plugged, with HDMI, I have an image. So at least it confirms that the port isn't defective on the graphic card.
But now, the second monitor isn't detected when I plug it with VGA. ( not by windows, or Nvidia config panel).

And, weirdly, with only the first monitor plugged in HDMI, windows somehow detect a second monitor, that obviously isn't there ( I double checked).


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#7
May 26, 2016 at 06:34:17
Just double checking here, but when you had the video card in PC2, did you also have two monitors hooked up, or just the one? I'm wondering if the GTX lost the ability to drive two monitors at the same time.

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#8
May 26, 2016 at 09:39:52
In PC2, both card can still manage 2 monitors. I didn't detect anything out of the ordinary when plugging my hardware in PC2.

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#9
May 26, 2016 at 11:12:31
If the hardware's behaving, then it has to be a driver issue. Download the latest Nvidia drivers, and make sure you use the clean install option when running the installer.

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#10
May 26, 2016 at 11:28:53
Ok, this is somewhat weird.
Since the day I got problems, I must have reinstalled my drivers half a dozen times.
I just did the same thing today ( clean install again, same version as the last time I tried).
And now my second screen is working ! I have no idea what I did different this time.
However, when I shut down the second screen, it is somehow still detected/registered. This doesn't bother much, but there is still an issue somewhere.
Anyway, thanks a lot for your help and your patience.

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#11
May 26, 2016 at 15:51:32
Yeah, I've had the same problems with Nividia drivers and HDMI. Not sure why it decided to act up on you, but I'm glad at least both monitors are showing video again.

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