There are two main PFC, one called Active PFC, another is passive PFC.

Active PFC itself is equivalent to a switching power supply, driven by controlling the chip switch on the input current modulation, and make it as far as possible simultaneously with the voltage,the value of Power Factor Correction can reach more than 98%, so often used the power supply with Active PFC circuit ,its energy conversion efficiency is in more than 80%, it is far more than the general passive PFC circuit, but its costs are relatively high, accounting for almost the entire power supply to the overall cost of 2-3%. Passive PFC,the value of Power Factor Correction just can reach about 75%, and the energy conversion efficiency is about 50%.

For example,one 300watts power supply with active PFC, its energy conversion efficiency is 80%, then it requires 375watts Alter Current;On the contrary, a low efficiency 300watts power supply with passive PFC,the energy conversion efficiency is Only 50%, then it needs 600watts Alter Current can be to output 300watts Direct Current to the computer, exactly a waste of 325watts.

Therefore, We recommend that you buy energy-saving power supply which must be first adopt active PFC power circuit design.our products such as the 1U、2U series used active PFC circuit design,it is popular in the industrial computer area for its strong stability and energy-saving now.