Question PC doesn't recognise second monitor

[peklarg]

So I have my PC connected to my AOC monitor and I am trying to add a second monitor but it just doesn't work.
Second monitor is Samsung T24A550 - LED monitor with TV tuner. I have it connected via HDMI cable to my PC but it doesn't recognise it.
I tried to connect that monitor to my laptop and it works fine. Cables are new and working as well as all ports, so I have no idea how to fix this.
If anyone have any idea how to deal with this problem please help. Thank you.

PS: English is not my first language so if there is something is not understandable just say it I will try to rephrase myself.

 

[DrummerManSpike]

Try updating your graphics driver (nvidia or amd/radeon). When I built my PC, only one monitor showed up at a time until I updated the driver. Also, plug in just the new monitor and not the existing one to see if the problem is with the monitor itself or your PC.

 

[peklarg]

I did all of that already. I updated graphics driver with the latest update and it did nothing.
When I plugged in only 'new' monitor it didn't work same as when I already had working monitor plugged in. But this 'new' monitor works when I connect it with my laptop or when I when I plug in the cable for TV.
Could it be that the PC is somehow too strong to for this monitor to handle or something? I don't really know much about computers so that could be just a ridiculous claim. I can post here my PC specifications if it would help somehow.
Also: I have to use an adapter to connect my working monitor to PC. I used the same adapter with non working monitor as well as just using HDMI cable or DVI cable and it is not working with either. But it is working with HDMI cable when I connect it to my laptop so I have no idea what is going on.

 

[peklarg]

I used the same cable as I used with the working monitor, the HDMI cable and the DVI cable. Non of them worked.
When I go to display settings on woking monitor and try to detect this non monitor it doesn't detect it but it does something because when I check 'sources' on this non working monitor it detects that HDMI cable is connected (other sources are TV, Ext., and PC - pc never did anything) but it still says that there is no signal on screen.
It doesn't make any sense why it wouldn't work.

EDIT: I tried with VGA cable not DVI sorry.

 

[peklarg]

Here is what I wrote about this problem in another forum. It is written a bit better and I think it is easier to understand:

Now I don't know much about computers but I try my best to explain my problem. If there is anything that doesn't make sense or I didn't mention something important please say what and I will try to rephrase myself.
I have a PC connected to my working AOC monitor and I have another monitor in my room that I used to watch TV (Samsung T24A550 - LED monitor with TV tuner). I don't really watch TV anymore so I wanted to use this monitor as my second monitor on my PC and it doesn't work.
Working monitor is connected to NVIDIA Quadro P620 graphics card. If I understand correctly it is connected with mdp 1.4 to DP cable and then DP to HDMI cable (does that make sense?). This monitor works perfectly. When I try to connect my second monitor with the same cables as first monitor it doesn't work. I also tried to connect PC to second monitor directly with HDMI cable and also directly with VGA cable but neither worked.
There is nothing wrong with the cables or with the ports on PC or second monitor. When I connect this non working monitor with my laptop with HDMI cable it works without a problem so monitor is in good shape aswell. My graphics card is updated with the latest update.
Now there is one thing I noticed when I have both monitors connected to PC. When I go, on my working monitor, to Display setting and try to detect second monitor it says that the second display is not detected. At the same time something happens on non working monitor because HDMI1/DVI source is detected on the 'source page' alongside with TV, PC and Ext. but it just says that there is no signal. So I guess there is some connection with PC and monitor?
If anyone has any idea how to fix this please help. I will try my best to do as you say and will inform you if it helped or not quickly as possible. Thank you.