Power Supply does not seem very important, but yet it is involved in the operation of a PC on it when it is precisely the problem.
A diet is chosen according to several criteria:
Training and equipment available
What power for your PC?
Modern CPUs consume little, because they are engraved with great fitness (45 nm beginning in 2008), but graphics cards are not as good ones: If a graphics card Midrange consumes about 50 to 100 W in 3D , high-end dual-GPU approaching 200W.
Choose a diet that is a good brand.
Antec, Corsair, Enermax, Fortron, Seasonic: these are well-known brands of manufacturers of food (except Corsair, Seasonic based), there is nothing to fear with these brands, their power will provide Watts announced.
Conversely, a diet known as "no name" will not be able to provide a continuous power Announced: It is not uncommon to find 480W "no name" actually providing less than half continuously since to better sell at low prices, it announced that Watts will be provided a few seconds, after which food and too much heat will safely (if any ...).
The "entry ticket" to quality is represented by the Earthwatt Antec 380W about 40 €. Based on the Seasonic S12 II 500W, it is very powerful for its price.
Do not take food too tight, she would regularly security, not too powerful, its performance is not good, since the return of an optimal diet is between 20% and 100% load, with up to 50% .
This can be done to help a very small program, the Power Supply Calculator (PSC) and Antec Outervision. All CPUs, even overclocking and all graphics cards are listed, so no mistake, we get the power required to configure, just take one of the values of trade one of them a little above, for example if CCS provides 382 W, a 500W will do, giving a maximum between 100W and 500W load.
Taking a small margin, it optimizes performance, and it has a reservation if you want to climb later a 2nd graphics card SLI or CrossFire.
Sizes and types of equipment
The power of trade may have different sizes and finishes, such as cable sheathing, detachable cables, the number of Sata taken or PCI Express ...
The most common is the ATX format, size 15 cm x 14 cm x 8.6 cm.
The power supplies in this format are easily interchangeable.
There are also smaller, usually for the barebones or mini PC.
The power supplies are difficult format interchangeable.