When the computer is turned on, the power flashes and the power goes out, what is going on How to so

After pressing the power button, the computer does not respond at all.

Please check the power cord and power socket, if it still doesn't work, please check the host power supply, if you are sure that there is no problem with the host power supply, please check whether there is a problem with the power button, the specific method is to find the power jumper on the motherboard, use a screwdriver to directly short the power jumper, you can find out whether it is a problem with the power button, you can consider replacing the restart button with the boot button, this situation is not much, and then it doesn't work, it is the problem of the motherboard or the motherboard power wiring.

2) The computer starts up and there is a fan sound, but the screen is not displayed.

Please check the CPU, fan, and CPU power outlets, graphics card, and finally consider the motherboard.

3) The computer starts, the screen is displayed, but you can't enter the Windows system.

Please repair or reinstall the system, if the hard disk cannot be found, please check whether the corresponding interface is prohibited in the CMOS, if there is a problem with the hard disk partition table, please reformat it. If it is a blue screen, please check whether the CMOS hard drive is in the correct format.

4) The computer can enter the system, but it cannot log in.

Please check if there is an error in the boot file, if you have forgotten your password, or if you have opened the numlock key.

5) The computer can log in, but the desktop cannot be seen.

If the power supply can't keep up, it may also be that there is a problem with the motherboard, in short, there is a problem with the hardware.

If the power supply fails, you can try it like this, unplug the largest plug between the power supply and the motherboard, and then power it on, at this time the fan inside the power supply should not rotate.

Find a wire, short circuit the green wire in this largest plug with any black wire, the fan inside the power supply should start to run after the short circuit, as long as the short circuit does not touch the fan, it will be rotating, and the fan will stop after the short circuit is lifted, at this time, the power supply reaction under normal circumstances.

There is a problem with the boot circuit of the motherboard, such as clock, reset, CPU power supply, MOS tube.

If there is a virtual welding failure, it may cause the machine to not be able to turn on, and there will be a virtual welding problem in the IO, Nanqiao, etc., and there will also be frequent black screens.

And can't turn on, wait, the solution: is to repair the motherboard, (if during the warranty period and after-sales service).

The video memory of the graphics card.

There is a virtual solder, VGA connected transistor, chip resistor.

If there is a problem with the capacitor, the performance of the main chip is reduced, the BIOS of the graphics card is out of order, and there is a problem with the control power IC, the graphics card will not work properly, resulting in a black screen. Jianyi repairs the graphics card, adds soldering to the video memory, replaces the main chip, etc., or replaces the graphics card.

Due to the short circuit, when the short circuit exists, the power supply is turned on, and the power supply immediately enters the overload protection state, and the power supply will be restored after a while. After the short circuit disappears, the power can be turned on normally. The solution to this situation is to remove all boards and external devices (hard drives, optical drives, etc.) to see if the smallest system can boot, and if not, repair the motherboard and power box.

Normally, install the previous devices one by one, one at a time, and test the startup situation several times until you find a problem.

This answer applies to most computer models such as the Dell vostro 3668.