Power
The output power of the power supply, in other words, is the maximum power that it is capable of delivering to the system. For the computer to operate efficiently, the power supply must be greater than the total power consumption of the system at maximum load. The latter can be calculated by summing the power of individual components, however, in general, for office configurations
, about 400 W —
450 W is considered sufficient, for medium gaming — about
600 W(
500 W,
550 W,
650 W,
700 W,
750 W), and for the top ones —
power of 800 W and above (
850 W,
1000 W and even
more than 1 kW).
Form factor
The form factor determines, first of all, the dimensions, and, as a result, the purpose of the power supply. To date, there are such main form factors:
—
ATX. Conventionally, it can be called "standard" — this is the most common form factor for regular-sized desktop PCs (in Full Tower and Midi Tower cases).
—
TFX. Compact form factor, designed specifically for small cases (in particular, Mini Tower). Due to their intended use, these power supplies are typically lower than full-sized ATX power supplies, while electrically they are fully ATX compliant.
—
SFX. Modification of the ATX form factor, developed at the end of the 20th century as a power supply option for systems in miniature microATX and FlexATX form factors (the S in the name stands for "small", i.e. "small"). Accordingly, the main difference is the dimensions: they are much smaller and amount to (width-depth-height) 100x125x64 mm with a standard 60 mm fan. When installing larger or smaller fans, the height of the unit changes accordingly; there are other deviations from the standard (for example, a slightly greater depth). The power connectors are almost identical to the original ATX, and these two standards are considered completely interchangeable.
Efficiency
Efficiency, in this case — the ratio of the power of the power supply (see "Power") to its power consumption. The higher the efficiency, the more efficient the power supply, the less energy it consumes from the network at the same output power, and the cheaper it is to operate. Efficiency may differ depending on the load; the characteristics can indicate both the minimum efficiency and its value at an average load (50%).
It should be noted that compliance with one or another level of 80PLUS efficiency directly depends on this indicator (for more details, see "Certificate").
Fan size
The diameter of the fan(s) in the power supply cooling system.
The large diameter allows to achieve good efficiency at relatively low RPMs, which in turn reduces noise and power consumption. On the other hand, large fans are more expensive than small ones and take up a lot of space, which affects the dimensions of the entire PSU. We also emphasize that a small fan is not yet a sign of a cheap power supply — quite advanced models can also have such equipment, in order to reduce dimensions.
As for specific diameters, the smallest value that can be found in modern consumer-grade PSUs is
80 mm. The most popular option is
120 mm, this size gives good efficiency and a relatively low noise level at a reasonable price and dimensions. Larger diameters are somewhat less common —
135 mm and
140 mm.
Cybenetics Efficiency
Cybenetics Efficiency is a power supply unit (PSU) energy efficiency certification system that serves as an alternative to the 80 PLUS standard. It is more accurate as it considers efficiency at various load levels (10%, 20%, 50%, 100%) and at different input voltages (115V, 230V). The labeling of this system is identical to 80 PLUS:
Bronze — overall efficiency from 82% to 85% at 115V input voltage and from 84% to 87% at 230V;
Silver — 85 – 87% and 87 – 89% respectively;
Gold — from 87% to 89% (115V) and from 89% to 91% (230V);
Platinum — 89 – 91% at 115V and 91 – 93% at 230V;
Titanium — 91 – 93% (115V) and 93 – 95% (230V);
Diamond — ≥ 93/95%.
Cybenetics Noise
The Cybenetics Lambda certification system evaluates the noise level of power supplies (PSU), providing consumers with information about their acoustic characteristics. As a result, you can rely not only on the efficiency of the power supply but also on its noisiness. There are the following Cybenetics Lambda certification levels:
Standard — from 40 dB(A) to 45 dB(A) – noticeable noise;
Standard+ — from 35 dB(A) to 40 dB(A) – distinct noise;
Standard++ — from 30 dB(A) to 35 dB(A) – moderate noise;
A- — from 25 dB(A) to 30 dB(A) – moderately quiet;
A — from 20 dB(A) to 25 dB(A) – quiet;
A+ — from 15 dB(A) to 20 dB(A) – very quiet;
A++ — less than 15 dB(A) – virtually silent.
ATX12V version
A standard for power supplies that supplements the ATX specifications regarding power supply along the 12 V line. Introduced into use since the time of the Intel Pentium 4 processor. In the first series of the standard, the +5 V line was mainly used; from version 2.0, the +12 V line was introduced to fully power the components computer. Also in the second generation, a 24-pin power connector appeared, used in most modern motherboards.
MB/CPU power supply
The number and type of connectors provided in the PSU to power the motherboard or processor.
This parameter is written as the sum of several numbers, for example, "24+4". The first number in such an entry means the number of contacts in the connector for powering the motherboard; in the vast majority of cases, this is just 24, since modern motherboards use a 24-pin connector as standard. The second number describes the socket for powering the processor; most entry-level and mid-range CPUs use 4-pin power, but powerful chips may require 8-pin power. There can be several 4- or 8-pin connectors — based on powerful high consumption processors.
A separate case is the blocks of the "24 (20 + 4)" format. They have two separate plugs — 20 pin and 4 pin, which allows you to power both 24-pin motherboards and older 20-pin motherboards from such power supplies. At the same time, such models do not provide a separate power supply for CPU — it is powered only through the socket, and the 4-pin plug cannot be connected to any other components except the motherboard.
Now on the market there are PSUs with such power supply for the motherboard:
24 pin (20+4),
24+4 pin,
24+8(4+4) pin,
24+8+8(4+4) pin.
SATA
The number of SATA power connectors provided in the PSU.
Nowadays, SATA is the standard interface for connecting internal hard drives, and it is also found in other types of drives (SSD, SSHD, etc.). Such an interface consists of a data connector connected to the motherboard, and a power connector connected to the PSU. Accordingly, in this paragraph we are talking about the number of SATA power plugs provided in the PSU. This number corresponds to the number of SATA drives that can be simultaneously powered from this model.