What is the reason for the Mac boot black screen question mark folder?

Cause analysis and elimination of failure:

I. Show

Black screen caused by monitor's failure to work normally due to its own reasons, such as poor contact of monitor power cord and power plug (note: both ends may be possible), power switch disconnection, and internal circuit failure of the monitor.

Two. Signal line

The display used in PC adopts the connection mode of 15-pin D-plug, in which 13 and 14-pin are synchronous signals of line and field. The display determines whether to open the filament and the high-voltage power supply path by judging whether these two signals exist, and at the same time, combining the positive and negative polarities of the signals and different line frequencies, these two signals are used as transmission signals in the display mode. If the line and field signals are lost, the power indicator of the display is green, but no image is displayed; If all are missing, the power indicator of the monitor is orange and no image is displayed. In this case, it is mainly to check whether the D-type plug of the display signal line has broken feet, crooked feet or short feet, and whether there is any disconnection inside the signal line. The solution is to replace high-quality signal lines.

We have a "video closing method" in the power management of CMOS settings of computers, in which "V/H SYNC+BLANK, BLANK.

Screen, DPMS "three options, the first is to select the display card to output line field signals to control the energy-saving mode of the display.

Three. Graphic card

The most directly related to the display is the graphics card. If there is no signal on the graphics card or there is a signal that cannot be sent out, the display screen will definitely not light up. In actual use, the display card is not compatible with the motherboard, the signal output socket of the display card is in poor contact or loose, which leads to the damage of the display card, and the poor contact between the display card and the AGP slot of the motherboard will lead to the display not being bright. Troubleshooting this kind of fault requires careful patience, carefully check the contact between the graphics card and the motherboard, and see if there is any unstable contact. Incompatibility can only be judged by experience and data.

Four. Power?Supply?

Everyone always spends more money on CPU and memory when configuring the machine, but always locks the door on the power supply. However, as the power supply of all computer components, if something goes wrong, can other components still work normally? As we all know, if there is a power failure, the host will give a continuous short beep alarm and the display screen will not light up. However, there are times when you say nothing. Finally, it was found that it was the power supply.

Verb (abbreviation for verb) mother board

The main reason is that CMOS settings are wrong. The first initialized graphics card is set to PCI or onboard AGP graphics card, but the monitor is not connected in the corresponding position. Results The computer started normally, but the display screen was not bright.

Furthermore, the conflict between CPU, memory or graphics card, sound card, modem and network card will also lead to the failure of the host computer to start, which will lead to the black screen of the display.

Software conflict of intransitive verbs

Due to the universality of PC and its strong vitality, thousands of software companies have been established in Qian Qian, and countless applications have been written for everyone. However, because these different applications are written by different companies, when they are put together, they may cause a black screen due to address call conflicts. The most typical feature of this fault is that after installing a certain software, the system prompts to restart, and after self-checking the screen and the blue sky and white clouds of WIN98, only the cursor flashes on the display screen, and then there is nothing. The solution to this kind of problem is also very simple. Just remember what software you just installed, hold down the "Ctrl" key when starting, select item 3 to enter the safe mode, and then uninstall the software you just installed.

Seven. Viral damage

Viruses are extremely destructive, especially with the advent of the Internet era, more and more viruses spread through the Internet. Viruses, such as CIH, which can lead to the black screen of the display, are extremely destructive, and directly rewrite the BIOS chip of the motherboard, resulting in the machine being unable to start and self-check. If there is no programmer, your motherboard can only be scrapped. Sometimes it may be because the BIOS chip is damaged by the virus, which leads to the misjudgment of the maintenance personnel and delays a lot of time.

If the virus maker understands the working principle of the graphics card and controls the output of the graphics card through the program, it will also cause the display to be black, but generally it can only be black after entering the system.