An ordinary power supply unit works with a voltage of 220 volts, but there are also options with a switch for a 110-volt solution. Such switches were created for operation in a European standard network, where electricity is supplied with a voltage of 110 volts.
There is also a 220 AC option, which means alternating current. The power supply for the computer converts an alternating voltage of 220 volts into stable 12 volts, 5 volts and 3.3 volts. After the conversion, the current in a constant state is supplied to the connected components of the computer. To power the microcircuits, contacts with a voltage of 3.3 and 5 volts are used. 12-volt wires are designed for the mechanical parts of the computer: fans and drives.
The power supply pinout of the old computer is not much different from the modern generation of power. The only difference is the addition of new power cables for modern equipment.
Pinout of the main power cable connector
The pinout of the computer's PSU begins with the largest and most significant power cable - this is the cable that connects to the motherboard. The old-style motherboards have an ATX connector for 20 contacts, and the new generation motherboards already have 24 contacts in their connector. For this reason, the new generation power supplies have cables with a 20 + 4 pin plug.
When pinning the computer's PSU, it is important to know that the ATX plug is only suitable for powering the motherboard. This can be checked if you look at the contacts in the plug and socket - each of them is unique and is suitable only for one purpose.
Molex Cable Description
The pinout of the computer's PSU connector, which contains only four parallel contacts, is called the “Molex”. As with the motherboard power cable, it is very difficult to make a mistake connecting this cable. It is suitable for powering floppy drives and hard drives.
Pinout of the PSU contacts of the computer for connection to the Molex connector:
- the yellow wire works with a voltage of 12 volts;
- two black wires in the middle are called “ground” and there is no voltage in them;
- the red wire carries a voltage of 5 volts.
Power pinout for SATA
To update the IDE interface, a new SATA cable was introduced , which contained 15 pins. In total, five wires are connected to the plug, each of which occupies three contacts. The first three contacts of orange color work with a voltage of 3.3 volts. The second three are COM pins, that is, ground. The middle pins have an input voltage of 5 volts. The fourth three are identical to the second. The last three contacts are already with a voltage of 12 volts.
In older versions of this cable, there were four wires of three pins, but with the update of the interface, support for 3.3 volts of input voltage was added, which is indicated by an orange wire.
EPS connector on 8 pin and 4 + 4 pin
In the pinout of the computer's power supply, you can find a cable with 8 power contacts, which is designed for the processor. The fact is that server- type processors require more power from the power supply, since they work constantly.
On the plug, the location of the contacts looks like this - the four upper contacts are marked as "ground", and the lower four contacts supply 12 volts of power.
The structure of the 4 + 4-pin cable is not very different from the 8-pin cable, but it is suitable for powering standard and server-type processors.
PCI Express Connectors
The 6-pin power cable is designed to work with video cards that consume no more than 75 watts. The location of the contacts indicates that the top three contacts supply voltage of 12 volts, and the three bottom contacts are responsible for grounding.
The 8-pin plug was put into production in 2007, as more powerful graphics accelerators began to appear at that time. Such a cable could provide power to a video card that does not require more than 150 watts. The pinout of the computer PSU with respect to this cable is as follows: four contacts arranged in two rows. The first and fifth through eighth contacts are responsible for the "ground", and contacts from the second to fourth supply voltage of 12 volts.
A cable with 6 + 2 contacts is the most versatile, as it can support both 6-pin video cards and 8-pin ones.
Determination of voltage by wire colors
In the production of standard power supplies for computers, there are certain standards that all well-known manufacturers strive to comply with, but there are exceptions.
Here is the exact definition of wires by color:
- black - Com, or ground;
- the yellow wire provides 12 volts;
- the red wire is responsible for supplying a voltage of 5 volts;
- The orange wire is powered at 3.3 volts.
Pinout of computer PSU under load
To test the performance of the power supply, you can connect it without affecting the system as a whole. This is done so that in case of a defective power supply, not to damage all components of the computer. For the initial start-up of the power supply, it is necessary to close the 6 and 7 contacts. If everything is done correctly, then the power supply should give a signal of operation in the form of a spinning fan.
Note: Pin counting does not include the additional four pins for the ATX connector.
How to choose a power supply
The power supply is the most important part of the system, which ensures the operability of all components. The choice of food should be approached with particular responsibility.
The first thing you need to pay attention to during a visual inspection is the presence of the braid of all cables. This is a good protection, or shielding, which allows you to suppress various types of waves and interference, due to which the operation of the entire system may be disrupted.
The second indicator is the presence of a certificate of quality guarantee - 80 PLUS, which guarantees the protection of the computer from voltage surges.
The remaining data is already determined by the presence in the system of parts with high energy consumption. It is better to buy a power supply with a margin, since the efficiency often does not coincide with the real figure.