【One update per day】Computer screen goes black

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This post was last edited by LLawliet on 2016-7-2 09:15. A black screen on a computer is a common issue, especially in older computers or custom-built PCs. There are various reasons for a computer screen going black, such as a damaged monitor, damaged motherboard, damaged graphics card, poor contact with the graphics card, damaged power supply, damaged CPU, or excessive temperature of components. In some cases, the computer screen going black is caused by human action. To address a black screen on a computer, the approach generally involves a combination of elimination and replacement, with the principle being to first replace the components that are most likely to be at fault. For ordinary computer users who lack specialized knowledge, they can follow the steps below to analyze the cause of the problem, so as to resolve it on their own. 　　First, check whether the connection is good. It is possible to check separately whether the connection between the graphics card and the monitor is good, as well as whether the connection between the graphics card and the motherboard’s I/O slots is proper. If necessary, it can be removed and reinstalled to ensure that it is properly installed with good contact. 　　If the connection works fine, it’s best to try another monitor to determine that there is nothing wrong with the monitor itself. 　　If the monitor is fine, check whether the CPU fan is running. If it is, use a multimeter to verify that the voltage output is within the normal range of ±12V or ±15V. If it is not, try using a different power supply. 　　If the screen remains black, remove all components installed in the computer, leaving only the CPU, graphics card, and memory modules; this way, the cause of the problem can be narrowed down to the CPU, motherboard, or memory. Generally, if there is a memory fault, there should be an alarm sound. If memory faults are ruled out, it’s only the CPU and motherboard left. 　　Replace it with a normal CPU (one that is compatible with the computer being tested), turn on the computer and conduct another test. If a black screen still appears, then it’s necessary to replace the motherboard, as the problem likely lies with the motherboard. 　　A black screen on a computer may indicate a serious issue with the device; it’s advisable to try the methods mentioned above to resolve the problem when this occurs. During the processing, exclusion and replacement methods should be applied flexibly to address phenomena that arise at appropriate times. 　 　1. When the monitor shows a black screen with no image displayed (although most monitors on the market will display “no signal connected” on the screen when no signal is sent from the computer), first check whether the power supply of the computer is properly connected and whether the fan of the power supply is spinning. Are the power indicator light and hard drive indicator light on the computer’s panel flashing or lit? Because if the computer’s power supply isn’t working or the motherboard isn’t receiving power, the monitor naturally won’t display any image since it receives no signal. 　　2. Check again to see if the power cable of the monitor is properly connected. If the power switch on your monitor is a touch-sensitive type, you should hear a slight \"click\" sound when power is supplied to the monitor; this indicates that the power supply circuit of the monitor is functioning properly. Is the power switch of the monitor turned on? Is the power indicator light on the monitor lit? When you bring your hand close to the monitor screen and move it slowly, does a \"hissing\" sound occur, along with a sensation as if the hairs on your hand are being pulled in? This is a way to check whether the high-voltage circuit of the monitor is working properly. 　　3. If it is confirmed that the monitor is powered on and high voltage is being generated, check again whether the data cable connectors of the monitor are in good contact with the signal output ports of the graphics card; are there any loose connections? Unplug the connectors to check for any bends or broken pins in the D-shaped connectors, as well as any excessive dirt. This is a problem that many users encounter frequently: when connecting the D-type connector, uneven force is applied, or the screws used to secure the connector are forgotten, resulting in a loose connection and poor contact. Alternatively, improper installation methods or excessive force can cause pins inside the D-type connector to break or bend, leading to poor contact as well. 　　Note: The 15-pin connector of the monitor’s data cable may be missing some pins, such as pins 4, 9, and 11; this is normal. Under no circumstances should other metal wires be used to fill in these missing pins, as this could cause other problems. 　　Pins 1, 2, and 3 are the input pins for red, green, and blue signal colors; if any of these pins is not in good contact, the screen will lack the corresponding color. 　　If there are issues with pins 12 and 15, the host computer will not be able to detect the corresponding monitor, but this does not affect usage. 　　If there is a problem with pins 13 and 14, the monitor will go black, and its indicator light will change from green to orange after it has been turned on for a while. And that’s when one of the aforementioned black screens occurred. 　　4. Open the case and check whether the graphics card is installed correctly. Is it making good contact with the motherboard slot? Has excessive dust accumulated on the graphics card or its slot due to prolonged use, resulting in poor connectivity? Are there any signs of burning or cracking on the chips of the graphics card? When a black screen occurs due to an issue with the graphics card, a short beep followed by four long beeps is emitted during the computer’s boot-up self-check. When installing the graphics card, hold the upper part of the card with your hand and insert it into the slot evenly, ensuring that the screw holes on the card align with those on the computer case. Do not force it into place if the timing is incorrect, as this may cause the graphics card to warp. If it is confirmed that the installation is correct, the graphics card can be removed and the gold contacts on its pins wiped clean with an alcohol swab, or it can be installed in a different slot (this is only applicable to PCI graphics cards). If that still doesn’t work, the only option is to try using a different, better graphics card. If that still doesn’t work, and it’s confirmed that the graphics card is in good condition, then the compatibility between the graphics card and the motherboard must also be considered. 　　5. Check whether the connections of other cards (including sound cards, decompression cards, and video capture cards) to the motherboard’s slots are proper. Make sure that the data cables and power cables connected to the hard drive are installed correctly. Try using different slots for those cards and clean the pins as well. This is something that many people tend to overlook. It is generally believed that a black screen on a computer is caused by issues with the monitor or graphics card, and has nothing to do with other devices. In fact, improper installation of devices such as sound cards makes it difficult to complete system initialization; in particular, connecting the data cable and power cable of the hard drive incorrectly can easily cause a no-display issue. 　　6. Check whether the memory stick is in good contact with the motherboard. Try resocketing the memory stick or using a different slot, or replace it with a new one. If there is a problem with the memory module, the computer will emit continuous rapid beeping sounds during startup. The beep sound will vary depending on the motherboard. 　　7. Check whether the CPU is in good contact with the CPU socket on the motherboard. Moving the computer or other factors may have caused poor contact between the CPU and the SLOT1 slot or the SOCKE370 socket. It’s best to press the CPU with your hand or remove it and reinstall it. 　　8. Check whether the jumpers or settings in CMOS for the CPU’s external clock frequency, multiplier, memory frequency, etc., are correct. Refer to the motherboard manual and check the relevant jumpers one by one, in the order of “CPU clock speed jumper – CPU multiplier jumper – memory frequency jumper”. 　　9. Check whether the CPU voltage is set properly. Be careful when setting the CPU voltage jumper; it must match the CPU’s operating voltage. Steps eight and nine should be carefully checked by those using certain assembly machines or users who like to overclock their systems when a black screen occurs. 　　10. Check whether the CMOS parameter settings are correct. If your computer has two graphics cards, and the CMOS settings specify that the first PCI graphics card should be initialized, while the only monitor is connected to the AGP graphics card, then of course the monitor will not turn on. 　　11. Check whether the working environment required by the host and monitor is met; whether the operating voltage is normal, and whether the ambient temperature is too high, etc. In addition to conducting the checks outlined above, it is also possible to locate the issue quickly by observing the computer’s operation status. For example, after turning on the computer, a \"beep\" sound indicates that the self-check has been completed; if the hard drive indicator light keeps flashing at this point, then checks should be carried out in steps two through four. 　　12. If the monitor displays content during computer startup but goes black only after the WIN98 screen loads, it is simply a problem with the WIN98 system software. 　　The aforementioned testing method is based on the assumption that there is no electrical fault with the monitor itself; that is, after turning on the power of the host, the monitor’s power indicator light changes from green to yellow, but the monitor remains black with no image displayed. If the display still shows no image after following the above steps, professional assistance should be sought for repair.