PC Power Supplies

Power Output

The power output indicates the maximum amount of Watts that the power supply can continuously supply to the components within the computer. In the following table, you will find the source supply in different systems.

Performance	Use	Configuration Example *
to 349GB	Lower class office and gaming computers	Intel Core i3, NVIDIA GeForce GTX 1050
350 to 499W	Middle-class gaming machines	Intel Core i5, NVIDIA GeForce GTX 1050 Ti
500 to 599W	Mid-range gaming machines	Intel Core i5 (K), NVIDIA GeForce GTX 1060 / GTX 1070
600 to 799W	High-end gaming machines	Intel Core i7 (K), NVIDIA GeForce GTX 1080 / GTX 1080 Ti
800W or more	High-end gaming computers, workstations, servers	Intel Core i7 (K), 2 × GTX 1080 Ti SLI

*These numbers are only estimations, the power consumption of processors may vary across generations. Other components are included in the total computer consumption.

Format of the PC Power Source

The format defines the physical dimensions of the computer source. The use of different formats is linked to different cases.

Source Format	Depth	Length	Height
ATX	140mm	150mm	86mm
SFX	100mm	125mm	63.5mm
TFX	175mm	85mm	65mm

Equipment for a Computer Source

Detachable cables - Some computer sources have a modular plug-in, allowing you to connect only the ones you really need. The result is better cable organisation, resulting in a cleaner look and better airflow.
Passive cooling - passively cooled sources do not contain a fan, they are cooled only by natural air flow, which can be potentially unhealthy for the system. Such sources, however, generally have limited performance. Some of the more powerful sources are able to passively cool down at low load, when higher they then activate a fan.
Active PFC - PFCs, or power factor correction power supplies smooth out current consumption and adjust the amount of power from the power supply. The aim is to prevent overload and voltage fluctuations. Active PFC for compensation uses a dedicated circuit and is a more expensive but better solution.
Passive PFCs - passive PFCs have the same task in a computer source as the active PFC, but they use a more common capacitive filter that reduces the cost but also the quality of the compensation. Passive PFCs can only be found in the cheapest sources.
Thermal speed control - thermal speed control is available in the vast majority of computer power sources. Its aim is to adjust the temperature rpm. The more heat that is generated, the faster the fan goes in order to maintain safe temperatures, while keeping the silent running.
The network switch - the power switch is familiar to everyone. It is a small two-state switch on the back of the power supply that can interrupt the power supply to a computer source.

Effectiveness of PC Power Sources

Efficiency is a parameter that indicates the percentage of electrical energy from a network that is used and divided between the components. The remaining percentages represent the amount of energy that is lost, which is given off as heat.

Although you can select a source directly based on the value of efficiency, it is better to use a standardised distribution using 80 PLUS certifications.

Certification	Efficiency*
80 PLUS	85%
80 PLUS Bronze	88%
80 PLUS Silver	90%
80 PLUS Gold	92%
80 PLUS Platinum	94%
80 PLUS Titanium	96%

*The values are calculated at 50% capacity at which the efficiency is highest.

Power Source Connectors

Each source has output connectors that must match their counterpart on the motherboard. When purchasing a power source, first look at what connectors your board requires, and then you can filter out which ones you don't want.

The motherboard's main power supply runs through a 20-pin or 24-pin connector, while the additional processor power is provided by the ATX 4-pin connector or 8-pin EPS connector.

i Specific values of the voltage levels at the outputs are 3.3V, 5V and 12V.

The power-intensive graphics card connection in the PCIe slot takes care of the same marked 6-pole or 8-pin power connector.

The 15-pin SATA connector serves to power all the relatively modern disks communicating through the SATA III interface. 4-pole Molex connectors, on the other hand, mount older HDDs, their reduced versions then FDD. Molex is the most commonly used connector on your computer, and a number of plug-and-play connectors for it can be used to connect any of the above-standard internal computer equipment.

Fan Size

The size of the fan of the computer source is mainly a consideration for the noise it generates. A larger fan can rotate slower to ensure the same air flow, reducing noise and increasing lifespan.

PC Power Supplies

Computer power supplies are standardized according to the ATX format, created in 1995 by Intel as a standard arrangement of components in computer cases. At that time, it replaced the older standard AT format. In 2003, Intel tried to replace it with BTX, but manufacturers did not switch to that format and instead ATX was revised several times. The latest and current versions are ATX2.2, and smaller formats mATX and Mini ITX.

As the ATX format developed, there were also changes in power supply - ie, in the area of computer resources. Therefore, it is now using ATX power supply for computer assembly versions 2.0, 2.2, 2.3 and 2.4 which differ in the main power connector, which plugs into the motherboard. It is therefore necessary for you to match the selected source to a version compatible with the motherboard.

When deciding which power source to buy, it is important to know the overall performance specification (given in watts and must be sufficient for the computer system - eg. For desktop computers 350-400 W is sufficient), cooling type and the amount and variation of additional power connectors.

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