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Why Isn’t My Second Monitor Detected?

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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


1 Answer

  1. 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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