Pulse Width Modulation (PWM) is a modulation of the duty cycle. The duty cycle reflects the switch between two fixed values, such as 0V and 5V. The frequency of the signal never changes in the process. The only factor that varies is the rhythm of "on time" and "off time". For example: a 50% PMW would set a fan – such a CPU or casing fan – running at approximately half of its maximum RPM.
A power supply delivers the necessary current to devices operated on the European 230V domestic network (or 110V in the USA and Japan). The power supply works here as a voltage convertor, converting the 230V alternating current into specific direct currents.
Active PFC stands for active Power Factor Correction. This is a filter to minimise disruptive harmonics. The highest possible value for an active PFC is 1.
The P4 plug is an important connector for a power supply. The plug was introduced by Intel with the Pentium 4 and has two contacts (pins) each for 12V current and earthing. It was introduced so that the processors receive power from a separate, uninfluenced 12V rail.
The PCI express (PCIe) slots is an extension of the PCI expansion slot. PCIe offers significantly higher data transfer rates of 250 Mbyte/s per data direction. PCIe is most frequently used as a graphics card slot. Because the PCIe slot has no more than 75 watts of power available, many graphics cards draw their power not just from the 6- or 8-pin PCIe slot, but from a 12V power supply as well.
The P8 plug is an extension of the P4 plug. It is equipped with eight contacts (pins), of which four provide 12V power supply and four are intended for earthing. The P8 plug is connected to the mainboard and is used for multi-core processors.
PF stands for Power Factor and in electronics refers to the ratio between real performance and apparent power. The power factor can be no more than 1. The closer to 1 the PF comes, the better that loss is avoided during transmission.