basics
PCIe
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.
P8
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 (PowerFactor)
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.
Quad-Rail
A quad rail is a 12V power supply split between four subrails. During the splitting of the individual voltage rails, the voltage remains at 12V, although the current is divided between the four subrails.
Rated Power Output
Rated power output refers to the nominal power output for a given power supply unit. The nominal power is the manufacturer's reported power output for that power supply. The nominal power is one of the general terms associated with power and hence is indicated in watts.
Reactive Power
Reactive power is an undesirable amount of electricity that constantly travels between source and consumer without being used effectively. It arises during the phase displacement between electricity and voltage. The use of a PFC in a power supply reduces the effect to a minimum.
SLI
Scan Line Interleave - SLI for short – describes the function that allows several graphics cards to operate within one computer. The 3dfx company first deployed SLI in 1996 to increase the performance of its Voodoo graphics cards. Today the term SLI is always used in relation to graphics card maker NVIDIA. SLI divides the graphics performance between two graphics cards running in one computer. This permits improved graphics performance.
Stable power supply
Switching power supplies convert the incoming alternative 230V current (in Germany) to direct current. This direct current is required for PC components (such as 3.3V, 5V and 12V). As the load increases, the voltage in the cables sinks, which leads to an unstable power supply for the components. A high-quality power supply stands out for low voltage fluctuations under load. Stable voltages in the cables hence provide a more reliable, uniform power supply.
Stand By
Standby is an operational state in which the device is held in a state of operational readiness to switch on. In many cases a red LED shows that the device is switched on but still in stand-by mode. Electronic devices continue to draw electricity even in stand-by mode.
Single Rail (operation)
Most power supplies separate the 12V current into several rails. Single rail refers to an operational approach that uses one undivided 12V rail. This has the benefit that more power is available at once through a rail. The disadvantage is the potential for collapsing voltages under high loads.