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What to do if the computer cannot see the monitor?

Adrian. 21. 21465 14
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  • #1 19126272
    Adrian. 21.
    Level 6  
    Posts: 39
    Rate: 1
    Board Language: polish
    The desktop computer is functional and does not detect the monitor... None when connected to DVI, VGA and HDMI, but the 14-year-old TV works when connected to the computer.
    Two laptops work when connected to 2 monitors via any cable, but neither monitor sees the desktop computer, I will add that the computer has a dedicated graphics card. What is the cause? The words NO SIGNAL appear on the monitors
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  • #2 19126292
    Kardor
    Level 15  
    Posts: 461
    Help: 13
    Rate: 100
    Board Language: polish
    What graphics card is this? What is the native resolution of these monitors?
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  • #3 19126304
    Adrian. 21.
    Level 6  
    Posts: 39
    Rate: 1
    Board Language: polish
    The monitors certainly support this resolution, one LG, the other Acer, the card is NVIDIA GEFORCE GTX 745 What to do if the computer cannot see the monitor?
  • #4 19126315
    Kardor
    Level 15  
    Posts: 461
    Help: 13
    Rate: 100
    Board Language: polish
    Is the refresh rate set to a value supported by the display in the graphics card settings?
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  • #5 19126327
    Adrian. 21.
    Level 6  
    Posts: 39
    Rate: 1
    Board Language: polish
    What to do if the computer cannot see the monitor?
  • #6 19126335
    Kardor
    Level 15  
    Posts: 461
    Help: 13
    Rate: 100
    Board Language: polish
    Try to change these settings, of course giving up the modes that the monitor cannot display. Interestingly, the card does not recognize monitors, except for PhilipsTV, so it can be assumed that either the connector or the card is damaged.

    Added after 3 [minutes]:

    Oh, I would have forgotten. Is the WIRE functional? Let's start with the smallest things :D
  • #7 19126349
    Adrian. 21.
    Level 6  
    Posts: 39
    Rate: 1
    Board Language: polish
    After all, if the card or connector was damaged, it wouldn't repair itself when the TV was connected, from what I can see, the monitor selects the paths itself when connecting laptops with different cables and always works
  • #8 19126364
    Kardor
    Level 15  
    Posts: 461
    Help: 13
    Rate: 100
    Board Language: polish
    But the monitor is not detected correctly by the card, it is displayed as Generic.
    Are your card drivers up to date?
  • #9 19126369
    Adrian. 21.
    Level 6  
    Posts: 39
    Rate: 1
    Board Language: polish
    All drivers are the latest
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  • #10 19127792
    CrisPell
    Level 11  
    Posts: 59
    Help: 2
    Rate: 5
    Board Language: polish
    Please specify the exact models of these monitors.
  • #11 19127900
    Adrian. 21.
    Level 6  
    Posts: 39
    Rate: 1
    Board Language: polish
    What to do if the computer cannot see the monitor? What to do if the computer cannot see the monitor? What to do if the computer cannot see the monitor?
    The first LG monitor has only a VGA input, it works normally on two laptops, the second monitor works on two laptops and has HDMI, DVI and VGA outputs, the third photo is a graphics card, when connected to both monitors via VGA NO SIGNAL on both monitors, after connecting via dvi (adapter) still No signal, by connecting display hdmi - hdmi still No signal, after connecting with the same cable to a 14-year-old TV everything works normally
  • #12 19127925
    CrisPell
    Level 11  
    Posts: 59
    Help: 2
    Rate: 5
    Board Language: polish
    And connect this monitor when you have an image on the TV and see if Windows is able to configure this screen.
  • #13 19127964
    Adrian. 21.
    Level 6  
    Posts: 39
    Rate: 1
    Board Language: polish
    I did this.... No signal
  • #14 19128180
    amp12
    Level 14  
    Posts: 98
    Help: 8
    Rate: 12
    Board Language: polish
    Dedicated graphics card, i.e. from the motherboard, not the processor and no additional one, as I understand it. So check the BIOS settings regarding the graphics card to boot from. Signal source selected appropriately in the monitor?
  • #15 19128212
    Adrian. 21.
    Level 6  
    Posts: 39
    Rate: 1
    Board Language: polish
    When connected to a laptop, the monitor works via VGA and HDMI without changing the signal source, it reads the path itself, and since the TV works normally under the computer, it means that the card has the correct settings

    Added after 7 [hours] 54 [minutes]:

    It only works via a DVI cable (double-sided), I close it
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Topic summary

✨ The discussion revolves around a desktop computer that fails to detect two monitors while functioning correctly with a 14-year-old TV. The user has an NVIDIA GeForce GTX 745 graphics card and has tried various connections (DVI, VGA, HDMI) without success, receiving a "NO SIGNAL" message. Participants suggest checking the graphics card settings, refresh rates, and ensuring the monitors are recognized correctly. The user confirms that the monitors work with laptops and that all drivers are up to date. Further troubleshooting includes checking BIOS settings and ensuring the correct signal source is selected on the monitors. Ultimately, it is noted that the monitors only work via a DVI cable.
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FAQ

TL;DR: Only 1 display was recognized; "Try to change these settings" and rule out bad cables or modes first. [Elektroda, Kardor, post #19126335]

Why it matters: This FAQ is for desktop users whose PC won’t detect a monitor or shows “No Signal,” offering fast, low-risk fixes.

Quick Facts

  • DVI-D single‑link supports up to 1920×1200 at 60 Hz; dual‑link up to 2560×1600 at 60 Hz. [Digital Visual Interface]
  • HDMI 2.0 carries 4K at 60 Hz (18 Gbps total bandwidth). [HDMI 2.0 Overview]
  • Windows 10/11: Win+P cycles modes; Settings > System > Display > Detect forces discovery. [Troubleshoot external monitor connections in Windows]
  • Passive DVI‑to‑VGA adapters don’t work on DVI‑D ports; use an active converter for VGA. [Digital Visual Interface]
  • EDID conveys a display’s supported modes in a 128‑byte base block; GPUs auto‑configure from it. [VESA Enhanced EDID Standard]

What’s the quickest fix to try first when my PC won’t see a monitor?

Use a direct, like‑for‑like cable between GPU and monitor. Connect DVI‑to‑DVI if both sides support it. In the reported case, a native DVI cable restored the picture. [Elektroda, Adrian. 21., post #19128212]

Why do my monitors say "No Signal" but the old TV shows an image?

Your GPU may detect only the TV, not the monitors. As one helper observed, "the card does not recognize monitors, except for PhilipsTV." Try safer modes and another cable before suspecting damage. [Elektroda, Kardor, post #19126335]

How do I check if the refresh rate is set wrong?

Open your graphics settings in Windows or the NVIDIA Control Panel. Select a refresh rate your display supports, typically 60 Hz. "Is the refresh rate set to a value supported by the display in the graphics card settings?" [Elektroda, Kardor, post #19126315]

Could a bad cable or adapter be the cause?

Yes. Swap in a known‑good cable and test each port once. "Is the WIRE functional? Let’s start with the smallest things." If the message changes or the monitor appears, the original cable or adapter was faulty. [Elektroda, Kardor, post #19126335]

Windows shows "Generic PnP Monitor." Is that a clue?

Yes. That label indicates Windows did not identify the monitor correctly. One helper linked this to drivers and asked, "Are your card drivers up to date?" Update the GPU driver, reconnect the display, and check again. [Elektroda, Kardor, post #19126364]

Do BIOS settings affect which GPU or port outputs video?

Yes. Ensure the BIOS Primary Display uses the dedicated graphics card. Also confirm the monitor’s input source matches the cable type. As another helper asked, "Signal source selected appropriately in the monitor?" [Elektroda, amp12, post #19128180]

Can connecting the monitor while the TV is showing an image help?

Try it. Connect the monitor after the TV shows the desktop, then attempt configuration in Windows. This method aims to trigger detection for the second display. [Elektroda, CrisPell, post #19127925]

Will a simple DVI-to-VGA dongle work on my card’s DVI port?

Only if the port is DVI‑I with analog pins. DVI‑D ports carry digital only, so passive DVI‑to‑VGA won’t work. Use an active converter when you need VGA from a digital output. [Digital Visual Interface]

What resolution and refresh rate should I try first?

Start with 1920×1080 at 60 Hz to maximize compatibility. As a reference, HDMI 2.0 supports 4K at 60 Hz over 18 Gbps. If that works, step up to your monitor’s native mode. [HDMI 2.0 Overview]

How do I force Windows to detect an external monitor?

  1. Press Win+P and select Duplicate, Extend, or Second screen only.
  2. Open Settings > System > Display and click Detect.
  3. Select the display and set Display resolution to the Recommended value. [Troubleshoot external monitor connections in Windows]

Do I need to set the monitor’s input manually?

Often, yes. Some monitors do not auto‑switch. Enter the on‑screen menu and set HDMI, DVI, or VGA as needed. This was explicitly raised in the thread: "Signal source selected appropriately in the monitor?" [Elektroda, amp12, post #19128180]

If the monitor works on laptops but not on my desktop, what does that imply?

It suggests the monitor and cable can work, so focus on the desktop’s output path. The OP confirmed both monitors worked on two laptops. Diagnose the desktop GPU, ports, settings, and cabling. [Elektroda, Adrian. 21., post #19126272]

Could the GPU or its connector be faulty?

Possibly. If only a TV is detected, suspect a bad connector or the card itself. A helper concluded, "either the connector or the card is damaged." Verify with alternate ports and displays. [Elektroda, Kardor, post #19126335]
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