Introduction to Server Power Supply Technology and Standards

　　As the "power system" for the operation of the server, the overall performance of the power supply system is undoubtedly one of the keys to improving the availability and reliability of the server system. It not only realizes the necessary power supply for the keyboard, mouse, system clock, software power on and off, and provides the server network remote wake-up, but also realizes the whole machine scalability such as multi-channel processors, multiple high-speed large-capacity hard disks, and high-speed I/O peripheral load requirements. Sufficient power support is also required. In terms of the overall internal structure design of the chassis, the power supply system also contributes. For example, an effectively designed power supply fan can not only provide sufficient cooling for itself, but also adjust the heat dissipation of the entire chassis system; in addition, if the power supply system of this machine adopts a variable speed fan design, it can also adjust the speed according to its own and ambient temperature, and reduce its own heat and noise; and the use of redundant technology can further improve the reliability and availability of the local power supply. Therefore, when you are building a high-availability server network system, in addition to looking for a reliable UPS external power supply guarantee, you should not take the server's own power supply system lightly.

　　As the name implies, server power is the power used in the server. Like PC power, it is a switching power supply. Servers use a lot of accessories. The supported CPU can reach 4 or more, the mounted hard disk can reach 4 to 10 pieces, and the memory capacity can be expanded to 10GB. These accessories are big energy consumers. For example, the mid-to-high-end industrial standard server uses Xeon processor, and its power consumption has reached more than 80

Watts, and each SCSI hard disk consumes more than 10 watts of power, so the power required by the server system is much higher than that of the PC. Generally, a 200-watt power supply is sufficient for a PC, while a server requires a high-power power supply of more than 300 watts or even thousands of watts.

　　Server power supplies can be divided into two types according to standards: ATX power supplies and SSI power supplies. The ATX standard is more commonly used, mainly for desktops, workstations and low-end servers; while the SSI standard was created with the development of server technology and is suitable for servers of all grades.

　　ATX Standard

　　The ATX standard is a specification introduced by Intel in 1997, and the output power is generally between 125 watts and 350 watts. ATX power supplies usually use a 20-pin double-row rectangular socket to power the motherboard. With the launch of Intel's Pentium4 processor, the power supply specification was changed from ATX to ATX12V. Compared with the ATX power supply, the ATX12V power supply mainly adds a 4-pin 12V power output terminal to better meet the power supply requirements of Pentium4 (the power consumption of the P4 with a main frequency of 2GHz reaches 52.4 watts).

　　SSI Standards

　　The SSI (Server System Infrastructure) specification is a new server power specification launched by Intel and some major IA architecture server manufacturers. The SSI specification was launched to standardize server power technology, reduce development costs, and extend the service life of servers. It mainly includes server power specifications, backplane system specifications, server chassis system specifications, and cooling system specifications.

　　Depending on the environment and scale of use, the SSI specification can be divided into four sub-specifications: TPS, EPS, MPS, and DPS.

　　The EPS specification (Entry Power Supply Specification) is mainly designed for low-end and mid-range servers powered by a single power supply. The design follows the basic specifications of the ATX power supply, but there are some differences in electrical performance indicators. It is suitable for power supplies with a rated power of 300 watts to 400 watts, and is used independently and not in a redundant manner. Later, the specification developed into EPS12V (Version 2.0), and the applicable rated power reached 450 watts to 650 watts. The most intuitive difference between it and the ATX12V power supply is that it provides a 24-pin motherboard power interface and an 8-pin CPU power interface.

　　The TPS specification (Thin Power Supply Specification) is applicable to systems with a power supply range of 180W to 275W, and has PFC (power factor correction) and automatic load current distribution functions. The power supply system can achieve up to 4 groups of power supplies in parallel for redundant operation, and the system provides fan cooling. The TPS power supply has high requirements for hot plugging and current balancing distribution. It can be used for N+1 redundant operation and has redundant protection functions.

　　The MPS specification (Midrange Power Supply Specification) power supply is defined for high-end server systems with more than 4 CPUs. The MPS power supply is suitable for power supplies with a rated power of 375 watts to 450 watts and can be used alone or redundantly. It has functions such as PFC and automatic load current distribution.

　　The DPS specification (Distributed Power Supply Specification) power supply is a power supply system with a single 48V DC voltage output, providing a minimum power of 800 watts, and outputs +48V and +12VSB. The DPS power supply uses a secondary power supply method, and the input AC power is converted to 48V DC power after passing through the AC-DC conversion circuit. The 48VDC is then converted to +5V, +12V, and +3.3V DC power required by the load through the DC-DC conversion circuit. This specification was formulated mainly to simplify the power supply method for telecom users, facilitate power supply in the computer room, and make the IA server power supply compatible with the power supply system used by telecom.

       Application-oriented. Although there are two standards for server power supplies, ATX and SSI, as the SSI standard becomes more standardized, the SSI standard is more suitable for the development of servers, and future server power supplies will also adopt the SSI standard. The SSI standard is conducive to the development of IA servers. In the future, the supported CPU main frequency will be higher and higher, the power consumption will be higher and higher, the hard disk capacity and speed will be higher and higher, and more and more high-speed devices can be plugged in. In order to reduce heat and save energy, the future SSI server power supply will develop in the direction of low voltage, high power, high density, high efficiency, and distribution.

　　In actual selection, different applications have different requirements for server power supplies. Industries such as telecommunications, securities, and finance emphasize data security and system stability, so server power supplies must have high reliability. Currently, high-end servers mostly use redundant power supply technology, which has functions such as current sharing and fault switching, which can effectively avoid the impact of power failure on the system and achieve 24×7 non-stop operation. The more common redundant power supply is N+1 redundancy, which can ensure that the system will not be paralyzed if one power supply fails (the probability of more than two power supply failures at the same time is very small). Redundant power supplies are usually combined with hot-swap technology, that is, hot-swap redundant power supplies, which can unplug the faulty power supply and replace it with a good power supply while the system is running, thereby greatly improving the stability and reliability of the server system.

　　However, I would like to remind you that although servers are different from PCs and cannot be DIYed casually, you should still pay attention to the power supply of the machine when purchasing. At least you should pay attention to the following two points: 1. The quality of the power supply, including whether the output power, efficiency, ripple noise, timing, protection circuit and other indicators meet the standards or meet your needs; 2. Pay attention to the reputation, scale and support of the power supply manufacturer. Manufacturers with good reputation, large scale and timely support, such as Delta, FSP, and Xinju, are generally of more reliable quality and have better cost performance.

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