Reasons and solutions why the screen remains black in win7 safe mode

Generally, if the black screen is caused by software, it is no problem to enter safe mode. If the black screen is still black after entering safe mode, hardware issues must be considered.

Possible causes and solutions are as follows:

1. Computer host failure

(1) Failure caused by host power supply

Black screen failure caused by damage to the host power supply or poor host power supply quality is very common. For example, after adding some new equipment, a black screen fault appears on the monitor. After eliminating the quality and compatibility issues of accessories, the main cause of the fault is poor quality of the power supply and insufficient power. At this time, you may still hear the continuous sound of the internal speaker. The alarm sounds 12 times and replacing a high-power and high-quality power supply is the best solution to this type of failure. In addition, some motherboards have AT/ATX dual power interfaces, and incorrect jumper settings can also cause this type of failure.

(2) Failures caused by the quality of accessories

Poor quality or damage to computer accessories is the main cause of black screen failure on the monitor. For example, problems with the motherboard (and the motherboard's CMOS), memory, graphics card, etc. may definitely cause a black screen failure. The fault manifests itself as if the monitor light is orange. At this time, the quickest solution is to try replacing the graphics card, memory, or even the motherboard and CPU with the replacement method

(3) Connection quality between accessories

Incorrect or loose connection between the memory, graphics card, etc. and the motherboard is the main cause of black screen failure. Moreover, there is a problem with the connection between the graphics card and the monitor, which may also cause this kind of failure. Until the AT power supply is not plugged in correctly, or even if the hard disk or optical drive data cable is connected reversely, it may also cause a black screen failure at startup.

(4) Black screen failure caused by overclocking

Excessive overclocking or overclocking components that are not suitable for overclocking will not only cause a black screen failure, but also cause damage to accessories in severe cases. In addition, excessive overclocking or overclocking components that are not suitable for overclocking, poor heat dissipation, or the cooling fan is damaged and does not rotate at all during normal use, etc. will cause the system to self-protect and crash with a black screen.

(5) Black screen caused by other reasons

Others such as incorrect motherboard CMOS settings and incorrect motherboard clear CMOS jumpers can cause black screen failures. In this case, you can change the settings according to the motherboard instructions. . In addition, software conflicts such as driver problems and improper installation, improper DIY such as BIOS refresh errors, incorrect power management settings, hardware damage caused by vicious viruses (such as CIH), etc. may cause black screen failures. When you encounter this kind of fault, you might as well think more carefully and consider the cause of the fault, so that you can get twice the result with half the effort by knowing yourself and the enemy when solving the fault.

(6) The floppy drive has a floppy disk

If the floppy drive has a floppy disk, it will often cause a black screen when the computer is turned on or restarted, and the system cannot be entered. To avoid this situation, you can also cancel the floppy disk startup item in the BIOS.

2. The display itself fails

(1) Insufficient AC power supply

Insufficient power of the external power supply causes some old monitors or some power consumption A large monitor cannot start normally, which is one of the causes of black screen failure caused by the monitor itself. Or the external power supply voltage is unstable, too high or too low, which may cause the monitor to not work.

(2) Damage to the power switch circuit

Faulty monitor switch circuit is the main cause of black screen failure on the monitor. It can be as simple as a damaged power switch or an internal short circuit, or as common as a damaged switch tube or damage to its peripheral circuit components, etc.

(3) Damage to the output circuit.

Failure of the horizontal output circuit or the picture tube and its power supply circuit is also the main cause of the black screen failure of the monitor. In particular, damage to the high-voltage package is more common in some off-brand monitors that have been used for many years or are of poor quality, resulting in no-display black screen failure.

3. Bad contact with the graphics card

1. The monitor has a "black screen" and the power indicator light does not light up. Most of these faults are caused by the monitor itself. First, check whether the monitor power cord is connected properly, whether the power plug is in good contact with the 220V AC socket, and whether the monitor power switch is turned on. After confirming that the 220V AC power is correctly supplied to the inside of the monitor, it can be determined that the monitor is faulty.

2. The display has a "black screen" and the power indicator light is on. The fault location is complicated. The fault may occur in the display, display card, motherboard or signal cable. When testing, first adjust the brightness and contrast knobs, observe whether there are any changes in light and dark on the screen, and rule out the phenomenon of "black screen" caused by turning off the brightness and contrast. If the screen is still "black" after adjusting the brightness and contrast knobs, you should check whether the signal cable from the host to the monitor is intact and whether there is any breakage or disconnection fault; after confirming that the signal cable is intact, perform POST (POWER ON SELF TEST) Electrical self-test) detection. POST detection is a process in which the computer automatically starts executing the POST diagnostic program every time the power switch is turned on to detect whether the various system components of the computer are normal or not. As soon as a problem is discovered during testing, an error message or a series of beeps is provided to the operator. In the case of a "black screen" fault on the monitor, people cannot see the screen information detected by POST, but they can determine the location of the fault through a series of beeps.

3. One long, two or three short beeps. This signal (which may be repeated) indicates that there is a problem with the graphics card. You should turn off the power of the host, open the chassis, and check whether the graphics card and the expansion slot are in good contact. If you suspect an expansion slot problem, you can remove it by replacing the expansion slot where the graphics card is located. If the fault is still not eliminated, you can change the display card to another matching microcomputer for inspection. If the other microcomputer also has a "black screen" after changing the card, it is judged that the fault is with the display card; if the display card works normally on other microcomputers , the fault is on the motherboard.　　

4. Two short beeps. This fault may be caused by the motherboard and graphics card or the monitor itself (very unlikely). Turn off the power, disconnect the monitor, remove the graphics card, and restart the system. If the two short beeps still exist, the problem lies with the motherboard and the motherboard should be repaired. But if the sound becomes one long sound and one short sound, then maybe the correct POST process noticed that the graphics card is not present, and the power should be turned off and the graphics card should be reinstalled without connecting the monitor. Restart the system. If the two short beeps still exist during POST, the display card is faulty: but if you hear only one short beep, the display card is good. It is the monitor itself that causes this error signal. You should Repair the monitor. When the monitor is separated from the host and the host is powered on for testing, make sure there is always power during the POST process. During this period, you can observe the operation of driver A and judge its system function. After the POST process is completed, the A drive indicator light will turn on. When the drive stops, press the DIR A: command, the drive should spin again and the indicator light will light up again, which indicates that the system is functioning normally and the host system board is intact. After the above detection, the fault location of the "black screen" of the monitor can be determined.

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