Comparison be quiet! Pure Power 11 BN294 vs be quiet! Straight Power 11 BN281

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, 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").

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.

The bearing is the piece between the rotating axle of the fan and the fixed base that supports the axle and reduces friction. The following types of bearings are found in modern fans:

— Sliding. The action of these bearings is based on direct contact between two solid surfaces, carefully polished to reduce friction. Such devices are simple, reliable and durable, but their efficiency is quite low — rolling, and even more so the hydrodynamic and magnetic principle of operation, provide much less friction.

— Rolling. They are also called "ball bearings", since the "mediators" between the axis of rotation and the fixed base are balls (less often — cylindrical rollers) fixed in a special ring. When the axis rotates, such balls roll between it and the base, due to which the friction force is very low — noticeably lower than in plain bearings. On the other hand, the design turns out to be more expensive and complex, and in terms of reliability it is somewhat inferior to both the same plain bearings and more advanced hydrodynamic devices. Therefore, although rolling bearings are quite widespread nowadays, however, in general, they are much less common than the mentioned varieties.

— Hydrodynamic. Bearings of this type are filled with a special liquid; when rotated, it creates a layer on which the moving part of the bearing slides. In this way, direct contact between hard surfaces is avoided and friction is significantly reduced compared to previous...types. Also, these bearings are quiet and very reliable. Of their shortcomings, a relatively high cost can be noted, but in fact this moment often turns out to be invisible against the background of the price of the entire system. Therefore, this option is extremely popular nowadays, it can be found in cooling systems of all levels — from low-cost to advanced.

— Magnetic centering. Bearings based on the principle of magnetic levitation: the rotating axis is "suspended" in a magnetic field. Thus, it is possible (as in hydrodynamic ones) to avoid contact between solid surfaces and further reduce friction. Considered the most advanced type of bearings, they are reliable and quiet, but expensive.

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.

The number of PCI-E 8pin (6+2) power connectors provided in the PSU design.

Additional PCI-E power connectors (all formats) are used to additionally power those types of internal peripherals for which 75 W is no longer enough, supplied directly through the PCI-E socket on the motherboard (video cards are a typical example). In PC components, there are two types of such connectors — 6pin, providing up to 75 W of additional power, and 8pin, giving up to 150 W. And the 8pin (6 + 2) plugs used in power supplies are universal: they can work with both 6-pin and 8-pin connectors on the expansion board. Therefore, this type of plug is the most popular in modern PSUs.

As for the quantity, on the market you can find models for 1 PCI-E 8pin (6 + 2) connector, for 2 such connectors, for 4 connectors, and in some cases — for 6 or more. Several of these plugs can be useful, for example, when connecting several video cards — or for a powerful high-performance video adapter equipped with several PCI-E additional power connectors.

The presence of at least one Floppy power connector in the PSU.

Initially, this connector was intended to power floppy disk drives, hence the name. It is also known under the designation "mini-Molex". Anyway, this standard is generally considered obsolete, but it is still used by some specific types of components, and therefore continues to be used in power supplies.

The cable system used in the power supply. According to this parameter, modular, semi- modular and non-modular devices are distinguished, here are their features:

— Not modular. The classic version of the design, used in computer power supplies from the very beginning and not losing popularity to this day. The wires in such systems have a non-detachable design, and additional cables are not provided for connection. As a result, the user has to deal with only those cables that the manufacturer provided, without the ability to remove or replace them (the only modifications available are the installation of additional accessories such as an extension cord or splitter). Because of this, such PSUs are less convenient than modular and semi-modular ones: their wires are often excessively long, and some of them are not used at all, while such an “economy” further clutters up the case, worsening air circulation and cooling efficiency. On the other hand, these shortcomings can be reduced to almost zero with careful selection of the PSU and careful wiring; and non-modular systems themselves are distinguished by reliability and at the same time low cost. It is because of these features that they are most common nowadays.

— Modular. Systems in which each cable is made detachable; special sockets are used for fastening wires. Thanks to this design, you can optimally organize the space inside the PC —...for example, remove unnecessary wires so that they do not interfere with air circulation in the system unit; replace a cable that is too long with a shorter wire (or vice versa); swap cables, etc. At the same time, modular systems are noticeably more expensive than non-modular ones, while they are considered somewhat less reliable due to the presence of "weak points" in the form of removable cable mounts.

— Semi-modular. A kind of compromise between the options described above: some of the wires in such power supplies are made non-removable, some are equipped with modular mounts. This makes it possible to partially combine the advantages and compensate for the disadvantages of the two systems: semi-modular PSUs are less expensive and more reliable than modular ones, and at the same time more convenient than non-modular ones. Usually, in systems of this type, the most important wires have a non-removable design, which are almost guaranteed to be used when assembling a PC, and secondary cables are equipped with removable mounts and can be removed if not needed. However, the specific features of a semi-modular PSU should be specified separately.

The maximum values of current and power that the PSU can provide on individual power lines.

The power line can be simply described as a pair of contacts for connecting a particular load; one of these contacts is “ground” (with zero voltage), and the second has a certain voltage with a plus or minus sign, this voltage corresponds to the voltage of the power line. In this paragraph, it is + 3.3V (such power is present in 20- and 24-pin connectors for motherboards, in SATA power connectors and some other types of connectors).

In general, power and currents are rather specific parameters that the average user rarely needs — mainly when connecting high-power components such as video cards, as well as when starting a PSU without a computer to power other electronics (for example, amateur radio stations). It is also worth mentioning that the sum of the maximum powers on all lines can be higher than the total output power of the PSU — this means that all lines cannot operate at full power at the same time. Accordingly, when the PSU is fully loaded, some of them will produce less power than the maximum possible.