From the design point of view, usually take 300W Taiwan（从设计角度出发一般取300w台）

From the design point of view, usually take 300W Taiwan（从设计角度出发一般取300w台） From the design point of view, usually take 300W Taiwan(从 设计角度出发一般取300w台) Of 300W.Txt35 is a warm color of nature from the angle of design, discerning craftsmen to show it to perfection; warm is a music beat note, the delicate feelings of the singers to express it was really pure to send general 300w/ basically can meet the requirements of the the point of view of design, but also can be applied mechanically, point to cover, we can analyze computer power 1, CPU P2 - more than 30 watt P3 - maximum 60W or so P4 - maximum 84W (in the hands of gamers, if overclocking, use the largest 95W, and the use rate is extremely high) 2, integrated graphics at around 15W, and a separate card from ten tiles to seventy tiles have been widely used. 3, the monitor 17, "CRT" (with the example of MITSUBISHI below) 96W, and the LCD will be below 50W 4, the hard disk is currently ST hard disk maximum power 12.5W, notebook only 5W. 5, the network card, sound card, memory, and now I have not found the exact data, it is estimated that 15W is not excessive. 6, CD-ROM is generally around 10W 7, the power and the motherboard itself also have energy consumption estimates 15W 8, speakers take the usual use of bass bubble, for example, power at about 30W Take the above value, add up to P = 348.5 W Because each of the above devices is not used at the same time, you can make a coefficient Kx=0.8 Calculated power: Pn=0.8*348.5=278.8W So at design time, 300W/ station is more reasonable. PFC is a very important parameter in the computer power supply, the full name is the computer power factor, referred to as PFC, which is equal to the apparent power multiplied by the power factor, that is: power factor = actual power / apparent power. Power factor: power factor represents the ability of computer power to output active power. Power is the measure of the transmission rate of energy. In a DC circuit, it is the voltage V and the current A and the product. In the communication system is complex: there are some AC current in the load cycle is the transmission of electrical energy, it is called reactance current or harmonic current, it makes the apparent power (voltage Volt by current Amps) is greater than the actual power. The power factor is equal to the apparent power and the actual power, and the power factor is equal to the ratio of the actual power to the apparent power. The power factor is only an electric heater and a bulb linear load is 1, the actual power many devices and apparent power difference is very small, can be neglected, and like capacitive equipment such as the difference is very important in computer. A recent study in the American Journal of PC Magazine shows that the typical power factor of a computer is 0.65, i.e., the apparent power (VA) is 50% larger than the actual power (Watts)! Apparent power: the product of alternating voltage and alternating current, expressed as a formula: S=UI. In the upper model, S is the rated output power, the unit is VA (volt ampere), U is the rated output voltage, the unit is V, such as 220V, 380V and so on. I is the rated output current, the unit is A. Apparent power includes two parts: active power (P) and reactive power (Q). Active power is the part of direct work. For example, make the light shining, turn the motor, make the electronic circuit work, etc.. Because of this power after doing work into heat, can be directly been felt, so some people have a misconception that the active power as the apparent power, which is not only as a part of active power in power, with P=SCOS0 said: =UICOS UI - theta theta = F In the upper model, P is the active power, the unit is W (watt), F=COS theta is called the power factor, and theta is the phase difference of the voltage and current when the nonlinear load is different. Reactive power is the part of the power stored in a circuit without direct action, expressed as Q=Ssin, theta, =UIsin, theta. In the upper model, the Q is reactive power, and the unit is var (VaR). For computers and other electronic circuits operating on DC voltages, reactive power can not work at all. Ordinary users believe that computers and other devices require only active power without the need for reactive power. Since reactive power doesn't do work, what does it do?! So, of course, they think power factor is 1 of the best power supply. Because it gives the maximum output power. However, this is not the case. If there is a computer, rectifier when AC power input, get the pulsating DC voltage, if the voltage ripple of any industry, is provided directly to the computer circuit, there is no doubt that the circuit is not working properly. Although the power factor of the computer is close to 1, what's the use of this?. In order for a computer circuit to work properly, a smoothing DC voltage must be provided. This "smoothing" operation must be accomplished by the filter capacitor C, which is connected to the computer power rectifier. The filter is like a reservoir, in which a sufficient number of charges must be stored, and the operating voltage on the circuit remains constant when the gap between the rectified half wave is maintained and the normal level is maintained. In other words, even in the two pulse input power can be half wave when the voltage level of UC had no significant change, this function is implemented by the energy storage capacitor, the energy stored within the capacitor is the reactive power. Therefore, the computer is relying on reactive power support, in order to ensure that the circuit correctly use active power to achieve normal operation. Therefore, it can be said that computers need not only active power, but also reactive power, both of which are indispensable.