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).
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.
Certification
The presence or absence of an 80+ certificate for the power supply. This certificate indicates high energy efficiency: to obtain it, the efficiency (see above) must be at least 80%, and in different modes (20%, 50% and 100% of the maximum load). There are several degrees of 80+:
—
80+. The original version of the certificate, assuming an efficiency of at least 82% (at least 85% for 50% load).
—
80+ White. The second name of the original 80+ certificate (see above).
—
80+ Bronze — efficiency not less than 85% (for half load — 88%).
—
80+ Silver — respectively 87% (90% for half load).
—
80+ Gold — 89% (92% for half load)
—
80+ Platinum — 90% (94% for half load).
—
80+ Titanium — 94% (96% for half load).
The power factor (see "PFC Type") must be at least 0.9 for the lower levels and at least 0.95 for the Platinum level. Also note that for redundant power used in server systems, the efficiency requirements are somewhat lower.
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.
EPS12V version
The version of the EPS12V standard that the power supply complies with. The EPS12V standard was created primarily for high consumption PCs (with a power of more than 700 W, see "Power") and entry-level servers. Such power supplies have a 24-pin plug for the motherboard and an 8-pin processor power connector (sometimes more than one, see “MB / CPU Power” for more details). They are also more reliable than ATX12V. They are compatible with most ATX standard motherboards, however, in older motherboards, there may be problems with matching connectors, so this issue should be clarified separately (however, to solve this problem, in some power supplies, parts of the plugs are made removable, which allows them to be reduced if necessary to the dimensions of the connectors on the motherboard).
MOLEX
The number of Molex (IDE) connectors provided in the design of the power supply.
Initially, such a connector was intended to power peripherals for the IDE interface, primarily hard drives. And although the IDE itself is completely obsolete today and is not used in new components, however, the Molex power connector continues to be installed in power supplies, and almost without fail. Almost any modern PSU has at least
1 – 2 of these connectors, and in high-end models this number can be
7 or more. This situation is due to the fact that Molex IDE is a fairly universal standard, and with the help of the simplest adapters, components with a different power interface can be powered from it. For example, there are Molex - SATA adapters for drives, Molex - 6 pin for video cards, etc.
Braided wires
The presence of a braid in the complete wires of the system unit — for all or at least for some.
This feature has a positive effect on reliability, making the wire as resistant as possible to bending, abrasion, strong pressure and other similar influences; it also provides additional protection against accidental contact with sharp objects (for example, when repairing a PC). The disadvantages of braided wires, in addition to increased cost, are also increased thickness and greater rigidity than similar cables in conventional insulation. This can create some difficulties in organizing space inside the system unit.
Noise level
The noise level produced by the power supply.
Usually, the characteristics indicate the average value of the noise level during normal operation. The lower this value, the quieter the power supply and the more comfortable it is to use. However, it is worth noting that modern computer PSUs produce very little noise. So, in the quietest models, this figure
does not exceed 20 dB — this is no louder than the rustling of leaves in a light breeze, such a sound is almost inaudible and is quite acceptable even in a residential area at night. Also acceptable for this application are noise sources of
21 – 25 dB(corresponding to a whisper at a distance of about 1 m) and
26 – 30 dB(wall clock ticking). Noise
of more than 30 dB is already considered quite significant for computer PSUs; according to sanitary standards, such equipment in residential premises can only be used during the day.
When choosing a power supply for this indicator, it is worth considering a few points. First, noise reduction comes at a cost: it can affect the cooling performance and/or cost of the device. Secondly, the noise from the power supply is often lost against the background of louder PC components — for example, powerful cooling systems for the CPU or graphics card. Thirdly, the very environment where the PC is installed can be noisy — an
...example is an office or coworking. Thus, specifically looking for a low-noise model makes sense mainly in cases where maximum silence is crucial for you.