The performance is an important criterion when selecting a power supply, which many are not really aware of, however. If the power supply is too weak, it may happen that the computer did not regard or you risk that the computer crashes and thereby lose data. In addition, it comes through the overloading of the power supply to an unnecessary amount of heat, can hardly cope with the integrated fan. If you turn to select a very strong power supply, even though the PC is not forced, it comes again to an unnecessarily high power consumption.
Especially when repairing, upgrading or if you want to assemble individual components of a computer itself, it is important to calculate the correct power for the power supply. The aim is the need of all components to identify and pay special attention to the two largest consumers of electricity, the processor and the graphics card. However, other components such as motherboard, hard disk drive, optical drive, fan and main memory should be considered.
The method for calculating the required power can usually be found directly on the hardware components themselves, or from the manufacturer. Once you have determined the total electricity consumption of the individual components, one should choose a power supply on which, an additional buffer to the calculated value remains, so that the power supply is not constantly reaches its limit and thus premature aging is prevented. In addition, you will benefit from the buffer at the next hardware upgrade, because the tendency is more nowadays meaning that newly developed hardware components more rather than consume less power.
In general we can say that computers only for everyday office applications or surfing on the Internet are used, get along very well with 300W power supplies. Power supplies in older systems come in even with less than 300W, because they still do not have a dedicated graphics card, among other things, and often require idle only between 40W and 50W power. Even with greater stress they rarely need more than 100W. Computers that are used primarily for gaming or complex video and sound applications, but should apply at least a 400W power, because the graphics card and processor demand much more power in this case. Ideally, choose a power supply with at least 500W to 650W. Today already power supplies with 1200W are available in the market, but these are so far only rarely needed.