Comparison Chieftec A-90 GDP-650C vs Chieftec Navitas GPM-650C

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 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 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.

The maximum current that the PSU is capable of issuing to the 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. However, most often it is used in the + 12V format; and the -12V line performs mainly a service function, it is almost never found in other connectors, except for the motherboard power plug (for 20 or 24 pins).

The maximum current that the PSU is capable of issuing + 5Vsb to the power line.

For more information about power lines in general, see "+3.3V". Specifically, the + 5Vsb line is used to power the computer electronics in standby mode, when the main and only task of the system is to respond to pressing the power button. This does not require high power, so this figure rarely exceeds 3A.

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

See "Maximum current and power" for details on power lines in general. 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. So this indicator is one of the most important characteristics of any PSU.

Note that many power supplies have several separate + 12V power lines. In such cases, the total power is indicated here, which, usually, is divided equally between the lines.

The maximum power that the PSU is capable of delivering on the + 3.3V and + 5V power lines.

See "Maximum current and power" for details on power lines in general. Here we note that the power lines + 3.3V and + 5V are used both in the general connector for the motherboard (for 20 or 24 pins), and in specialized plugs — in particular, the SATA power connector (both) and Molex (only +5V, in addition to +12V). The power of these lines is a rather specific parameter, rarely required in fact; it is usually the same for both voltages, so it is indicated in the general clause.

The maximum power that the PSU is capable of delivering to the power line is -12V.

See "Maximum current and power" for details on power lines in general. Here we note that -12V is a rather specific format used exclusively in power plugs for motherboards — to supply power to individual motherboard components that require reverse polarity.

The maximum power that the PSU is capable of delivering to the power line is + 5Vsb.

See "Maximum current and power" for details on power lines in general. Here we recall that the + 5Vsb line is used to power the computer electronics in standby mode, when the main and only task of the system is to respond to pressing the power button. This does not require high power, so this figure rarely exceeds 15 watts.