Performance of modern computers is doubling almost every year, the clock just going wild, growing by leaps and bounds, and the processor cores are breeding like roaches .. Processor come with stunning margin of safety than is already used not only overclock, and almost every reasonable person. Computer hardware is becoming faster and more and hungry. In 2005, scoring 400 watt power supply was a rarity, but now it at least. Now nobody will be surprised and 1500 watt PSU, and in the home companies put a minimum of 500-600W. In choosing the components that will form our configuration, usually the power supply (ATX 2.xx) is overshadowed, whereas the latter only in light of the maximum power output.
A power supply converts the 230 volt AC outlet in the DC in order to deal as notebook and PC with just this. In addition, a power supply, the task of the computer through the Power-OK signal has to announce that all the tensions lie stable. A power supply has three power lines that are used by the different components: The current components such as CPU, DDR2/3-Speicher, PCI-Express graphics cards, SATA drives, but also fans use the 12-volt line. It is used most frequently and is divided into several strands. Older CPUs and memory modules and cards to use against the 5 - and 3.3-volt rail. In addition, the negative voltage power supplies provide -5 and -12 volts, which played only a role in older boards. For example, provide ISA slots -5 V and -12 V old-style serial controller is available. The latter now need less power and are therefore supplied by the 5-volt line. By the way: According Specification at all voltage lines only a deviation of + / - 5 percent is allowed.
A PC power supply is roughly speaking from a sheet metal housing with a Euro-IEC socket for connection to the outlet, a power switch and - depending on the model - one or more fans. The 230 volt alternating current from the electrical outlet is converted in the power supply of rectifiers and smoothing capacitors in DC. A transistor produces a rectangular voltage (AC) and chopped up the DC voltage into AC voltages of about 15 to 50 kHz. A transformer converts the single AC voltages in 3.3, 5 and 12 volts, which in turn by a rectifier and smoothing capacitors to voltages remodeled. These voltages are placed on the different voltage lines or power connector to the PCB and the components.
The 20 - or 24-pin power connector provides the interfaces and slots with +3.3, + / -5 and + / -12 volts. In addition to the live wires of the harness has four wires: ground (black), power-OK (gray), PS-ON (green) for the On and Off, Sense Amp (Brown) that the 3.3 volts exactly adjusts to compensate for losses such as cable or connector, and the standby voltage 5VSB (purple). Hard disks and other drives have per 4-pin PATA connector or SATA connector with 15 contacts their electricity. Both have two ground lines and the one 12-volt and a 5-volt channel. SATA drives require an additional 3.3 volts. For PCI-Express graphics card power supplies have special 6-pin connectors, which are connected to three 12-volt and three ground lines.
To turn now to absorb the power connections of the power supply to a circuit board needs two main terminals: the 20 - or 24-pin for ATX power connector and the 4 - or 8-pin for an additional 12-volt supply. The slots and interfaces, which are located on a motherboard to get, over the lines on the board the tension that they are entitled according to specification. Requires a component - such as a video card or CPU - more power than the slot can provide come, the extra voltage cables - in the case of video card or CPU of the 6 - and 8-pin 12-volt channel - is used.
ATX PSU :
The most common are ATX power supplies, as ATX (Advanced Technology extended) form factor, is for desktop PCs typically in use. A distinction between ATX Version 1.3, 2.0 and 2.2, with each version requires a different power connector to the motherboard. For ATX 1.3 of these so-called Molex connector is 20 poles in 24-pin ATX 2.0. Some CPUs like Intel's Pentium 4 need for ATX 1.3, furthermore, 4-pin 12-volt plug (AUX). ATX 2.2 also implies a 24-pin connector, here CPUs is also an 8-pin 12V connectors. That is missing the line that generates -5 volts. To the plug-maze to simplify somewhat, there are adapters that make, for example, from a 24-pin a 20-pin power connector. Or the 24-pin plug can separate, so that you can only use the 20-pin part. In the 8-pin 12-volt sockets, which provide some additional boards, but it is possible to equip it with a 4-pin connectors - if that's enough built-in components.
Usually a power supply manufacturer advertises the maximum power rating (in watts). But much more important than this is the combined performance. For it is the maximum power, which is actually available for PC power supplies. In the manufacturer's instructions, see either the maximum combined output of the 3,3 - and 5-volt lines and / or the 3,3 -, 5 - and 12-volt lines. If this value is not specified, you can deduct 20 to 30 watts by the manufacturer to get the combined value. However, you should be at the purchasing power needed to calculate not just because it usually comes to crashes and premature aging, when the power supply operates continuously at full load. And you should be ready for an upgrade, as new graphics cards and CPUs consume more rather than less power.
A power supply should have a maximum effect. This is the ratio between input and output, so how much of the recorded performance, the power supply is really passed on to the component. For some remains of electricity wasted as heat and leaves the PC case - which is reflected in the long run on the electricity bill. The ATX Power Supply Design Guide calls for an ATX power efficiencies of up to 65-75 percent at low load and 70 to 77 percent at full load. Power supplies, the efficiency of over 80 percent may have one, the " 80plus -wear label, "the July 2007, part of the specification for the Energy Star 4.0 is published.
Strength and power :
Another indicator of the quality of a power supply is the resilience of the individual tracks. For example, a 400-watt power supplies to the 3.3-volt line 23 to 30 amps. The 5-volt rail are available 28 to 30 amps on the 12 volt rail to 30 amps. At -12 V is the carrying capacity from 0.3 to 0.7 amps. Important: It may not all tracks can be operated simultaneously with the full power. Another point you should consider when buying a power supply is, the current consumption in standby mode. It should of course be as low as possible. Relevant information can be found in the technical data of a power supply.