The most detailed explanation of ATX power supply, please find out!

What is an ATX power supply? Below is a detailed explanation of the ATX power supply compiled by the editor. Please bookmark it!

1. The ATX power supply has two types: 20-pin and 24-pin, with black ground wire, orange 3.3V, red 5V, and yellow 12V.

2. The traditional power switch determines the working time of the machine, but this is not the case with the ATX power supply. It mainly relies on the +5VSB output and PS-ON output to determine the power switch. Through the control of the PS-ON signal, the voltage can be controlled to control the power supply. After the ATX power supply is shut down, the remaining weak current activates the Stand-B* function, so that the ATX power supply can be directly controlled through the operating system to achieve remote booting.

3. ATX power supplies are all potential control switches rather than mechanical switches. Therefore, you need to find the pin that can activate the power supply from the row of wire holes on the power supply.

4.20 pins

The standard definition of ATX power supply pin header (Pin) is:

Pin 14 PS-ON controls the power on and off. How can a single pin control the switch without a loop? In fact, all ground wires (GND) can form a loop with any other pin. The so-called "low potential" is turned on and the "high potential" is turned off. It means that when Pin 14 is short-circuited with the GND pin, The potential of Pin 14 itself is low, and the power is turned on, and vice versa. Now it's clear - if you want to turn on the ATX power supply without a motherboard, you only need to short-circuit Pin 14 (green wire, marked green in the picture) with any GND pin (black wire, marked gray in the picture).

5.24 pins

Power pin definition:

1. +3.3V; 2. +3.3V; 3. Ground; 4. +5V; 5. Ground; 6. +5V; 7. Ground; 8. PWRGD (good power supply); 9. +5V ( Standby); 10. +12V; 11. +12V; 12. 2*12 connector detection; 13. +3.3V; 14. -12V; 15. Ground wire; 16. PS-ON# (power supply remote switch) ;17. Ground wire; 18. Ground wire; 19. Ground wire; 20. No connection; 21. +5V; 22. +5V; 23. +5V; 24. Ground wire

6.What do the various voltages power?

6.1+12V

+12V generally provides power for the spindle motors and seek motors of hard drives, optical drives, and floppy drives, and provides operating voltage and logic signal levels for circuits such as serial ports for ISA slots. If the +12V voltage output is abnormal, the disk reading performance of the hard disk, optical drive, and floppy drive will often be unstable. When the voltage is low, the optical drive will pick up the disk seriously, and the logical bad sectors of the hard disk will increase. Bad sectors often appear, and the system will easily crash and cannot be used normally. When it is on the high side, the speed of the optical drive is too high, and it is easy to lose control and crash, and the hard disk stalls and spins.

6.2-12V

The voltage of -12V is to provide the logic judgment level for the serial port. The current required is small, generally below 1 amp. Even if the voltage deviation is large, it will not cause a fault because the 0 level of the logic level is -3 to -15V. , has a wide range.

6.3+5V

The +5V power supply is the working voltage provided to the CPU and integrated circuits such as PCI, AGP, ISA, etc. It is the main working power supply of the computer. The quality of its power supply is directly related to the system stability of the computer. The +5V output current of most AMD CPUs is greater than 18A, and the latest P4 CPU provides at least 20A. In addition, AMD and P4 machines require a +5VSB power supply current of at least 720MA or more, and P4 system computers require a power supply of at least 230W.

If there is not a large enough +5V voltage supply, the CPU will slow down, blue screens will often appear, screen images will freeze, etc., and the computer will become very unstable or unreliable.

6.4-5V

-5V also provides a judgment level for logic circuits. The current required is very small, which generally does not affect the normal operation of the system, and the probability of failure is very small.

6.5+3.3V

This is specially set up for the ATX power supply to provide power for the memory. The voltage requirements are strict, the output should be stable, the ripple coefficient should be small, and the output current should be large, above 20 amps. When most motherboards use SDRAM memory, in order to reduce costs, they output the power directly to the memory slot. Some mid-to-high-end motherboards use high-power field tubes to control the power supply of the memory for safety reasons. However, the tubes may be burned when the memory is plugged in. If the motherboard uses +2.5V DDR memory, the voltage conversion circuit is installed on the motherboard. If the voltage of this circuit is too low, it may easily crash or frequently report memory errors, or the WIN98 system may prompt registry errors, or the operating system may not be installed normally.

6.6+5VSB (+5V standby power supply)

The ATX power supply provides +5V 720MA power to the motherboard through PIN9. This power supply provides power for WOL (Wake-up On Lan), boot circuit, USB interface and other circuits. If you do not use functions such as network wake-up, please turn off such functions and remove the jumper to prevent these devices from drawing current from the +5VSB power supply terminal.

6.7P-ON (power switch end)

The P-ON terminal (PIN14) is the power switch control terminal. This port controls the working status of the main power supply of the switching power supply by judging the level signal of the port. When the signal level of this port is greater than 1.8V, the main power supply is off; if the signal level is lower than 1.8V, the main power supply is on. Therefore, when powering up the switching power supply alone, you can use a multimeter to test the output signal level of this pin, which is generally around 4V. Because the voltage output by this pin is a signal level, the switching power supply has an internal current-limiting resistor, and the output current is also within a few milliamps. Therefore, we can directly use a short wire or an open paper clip to directly short-circuit PIN14 and PIN15 (i.e. ground, and 3, 5, 7, 13, 15, 16, 17 pins), the switching power supply can start working. At this time, we can use a multimeter to test whether the output voltage of the switching power supply is normal while offline.

Remember: Sometimes although the power supply output voltage we tested with a multimeter is correct, the power supply still does not work when it is connected to the system. This situation is mainly because the power supply cannot provide enough current. Typical manifestations include irregular system restarts or shutdowns. So in this case we have to replace the power supply with a more powerful one.

6.8P-OK (power good signal)

Under normal circumstances, if the output of the gray line P-OK is above 2V, then the power supply can be used normally; if the output of P-OK is below 1V, the power supply will not guarantee the normal operation of the system and must be replaced.

6.9220VAC (mains input)

Generally, none of us care about the mains power supply used by computers, but it is necessary for computer work and is often ignored. When installing the computer, we must use a 220V mains socket with a good grounding device, and the variation range should be within 10%. If the variation range of the mains power is too large, we'd better use a switching power supply with a wide range between 100-260V, or use an online UPS power supply.

-Preparatory power supply

4-pin (1*4) interface, provides power for PCI Express x16 graphics card, 1. +12V; 2. Ground; 3. Ground; 4. +5V

8-pin (2*4) interface. Not all 915/925 motherboards have this reserve power interface. It can only be seen on some high-end motherboards.

For i915/925 motherboards, there are two common power supply combinations: one is 24-pin main power supply + ATX 12V, which can provide 144W of power for the motherboard. The second is the 20-pin main power supply + ATX 12V + backup power supply. The main power supply and backup power supply each provide 72W, and the total is 144W.

According to Intel's specifications, it provides 2A of +5V current for each card. If 6 expansion slots + PCI Express x16 are used at full load, they cannot exceed 14A, otherwise no matter how strong the power supply is, it will not be able to provide enough power. Excessive current may cause the motherboard to burn out.