Comparison Zalman Wattbit II ZM400-XEII vs 1stPlayer Black Widows PS-400SFX APFC

The type of power factor correction (PFC) provided in the power supply.

The power consumed by the PSU is divided into active and reactive; the first goes to perform useful work, the second does not produce such work and is dissipated in the form of heat. The power factor is the ratio of active power to the total power consumed; the closer it is to one, the more efficient the PSU.

PFC correction is applied to improve the power factor. It can be done passively or actively. The first option provides the presence of a coil (choke), which partly compensates for the operation of the reactive components of the PSU; such a correction is simple and inexpensive to implement, but not very effective. The active method, in turn, provides the presence of a specialized controller. It is more expensive, but the power factor in such PSUs can reach 0.95 or more; in addition, the device is more resistant to voltage drops.

In general, for use in a home or small office, passive correction is more than enough; active PSUs should be specifically looked for mainly in cases where we are talking about numerous computers connected to a powerful UPS.

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 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.

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 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.

The maximum current that the PSU is capable of issuing + 5V to the power line. For more information about power lines in general, see "+3.3V". Also note here that + 5V power, in addition to connectors for motherboards (for 20 and 24 pins), is also found in Molex and SATA plugs, as well as some other specific types of connectors.

The maximum current that the PSU is capable of delivering to the first power line is + 12V.

For more information about power lines in general, see "+3.3V". Here it is worth mentioning that 12 V is the most popular voltage among computer power connectors. It is used in almost all such connectors (with a few exceptions), and some plugs (for example, additional PCI-E power for 6 or 8 connectors) use only 12-volt lines — and in the + 12V format. And the division of + 12V power into several separate lines is used for safety purposes — in order to reduce the current flowing through each individual wire, and thus prevent excessive load and overheating of the wiring. However, some manufacturers do not specify the maximum current for individual + 12V lines and give only a general value in the characteristics; in such cases, this number is indicated in this paragraph.