PC Power Supply Buying Guide


Modern personal computers utilize direct current to power their internal components. Power supplied from the mains is often alternating current. A power supply unit is used to convert alternating current to direct current thus making the power suitable to use on the PC.

Types of Power Supplies

AT Power Supply

It is the power supply that was developed earliest. They are very easy to use. They use connectors that have six pins. The connector is also single-inlined. The connector is connected to the motherboard. The pins are arranged adjacent to each other. This type of power supply has to be used with an external load. Otherwise, it will not last long. Also, using it without external load could cause damage to parts of a computer. The AT power supply uses p8 and p9 connections to attach to the motherboard. These must be placed facing each other. The clips must face out. This arrangement is pretty simple and will ensure it provides optimum functionality.

ATX Power Supply

Its connector has twenty pins, and they are dual-inline. The connector is connected to the motherboard. It is not very easy to use since there many requirements that have to be attained. First, the green wire from the motherboard must be connected to the black wire of the supply for it to work. A switch can be utilized to attain this connection. This switch can be switched off if the user wants to suspend the PC or make it go into sleep mode. The wire on the eleventh pin of the connector has to be attached to a +3.3 V wire for the supply to work. The p1 power connector is the one used for connection to the ATX socket.

ATX-2 Power Supply

It is an improvement of the classic ATX power supply. It is the most modern and is currently the most widely used type of power supply. It has a twenty-four pin connector, which is also dual-inline. This connector is connected to the motherboard. Here also, the wires of pin 15 and pin 16 are connected. Also, more sense wires are connected to other wires, which have similar voltage and color. For instance wire on pin 13, which has a voltage of 3.3 and is orange is attached to a 3.3v wire, which is also orange in color.

Factors to pay attention to when Buying PC power Supply

Power Output

The output is usually indicated in watts. Most PC power supplies have an output of between two hundred and one thousand eight hundred watts. Any above one thousand eight hundred will not be compatible with regular mains. The higher the number of watts that a power supply unit emits, the greater the power supplied. A higher watt power supply would sufficiently supply a computer's components and have sufficient power left over to supply any other components that may be added. Typically, an efficient power supply utilizes between forty and eighty percent of its power. This range would, therefore, be maintained if a power supply that has a greater output by fifty percent than the total design power of the computer is utilized. Also, a high output does not necessarily mean that the supply uses a lot of power.

Type of rails

Power Supply Units normally have different kinds of rails. There are two types of rails; the single rail and multi-rail. The single rail uses one +12V rail to supply power to PC components. A multi-rail, on the other hand, uses more than one +12V rail to supply power to components. The best type depends on the level of safety one wants. If a short-circuit occurs when using a single rail power supply all computer components will be damaged since the power supply is from a single source. This would not happen with a multi-rail power supply. Apart from the safety factor, both rails work efficiently and would produce the same output.


A highly efficient power supply unit minimizes the amount of heat produced, minimizes waste of power and decreases the amount of noise emitted by the fan. At the same time, it ensures that most of the power is utilized by the computer components. Therefore, one must select only those power supplies with very high-efficiency ratings. For instance, if a power supply is rated eighty percent efficient, it means only twenty percent of the power is wasted. This is enough for an average PC user. Therefore, one must analyze the power supply's efficiency certification before making that purchase.


The type of cables in the power supply could affect the ease of use. Modular cabling would help one to de-clutter the case. They can be easily disconnected and reconnected when they need to be utilized. Modular cabling also increases the ease of cleaning since the cables can be easily removed to facilitate cleaning then reattached. Hard-wire is also the best kind of wire for a power supply. With hard wire, no further wiring is required between the connector and the internal components. This is because the hard wire is directly connected to an internal component.

Physical size

Power supplies are of different sizes. The appropriate size depends on the PC chassis. Most PCs have mid-tower cases, therefore, a very large power supply unit would not be able to fit in them. Buyers should select the size that will fit their cases. The size will also affect the ease of transportation.


Power supplies come at different prices depending on the type and manufacturer. Modular Power Supplies would cost more than the non-modular for example. Buyers should avoid excessively cheap power supplies from relatively unknown manufacturers as they will not last long enough. A poor power supply unit could lead to damage of computer components and in the long run it would be more expensive to replace those damaged parts. Experts postulate that if the power supply costs one dollar for every ten watts, then its performance would be good enough.

Top Brands and Product Lines

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