Any PC we want to assemble will not be complete without a power supply, and we need to spend time choosing the best one for our needs. Although there are usually sources that do not give bad results for prices as low as 20 euros, we are always in doubt: why are there fonts more expensive? The answer, like everything else, is in the quality of the source , and we explain here what point you have to consider before choosing the best psu brands.
The electronic components suffer a wear while they are used like any other product, but when they are taken out of their usual area of work they degrade much faster. While a 300 W power supply could give enough power to feed at 350 W or more, it would suffer a rapid wear that in days, weeks or months would stop working. So you have to consider some things when buying a power supply.
Efficiency of the source
The first is that the indicated power is not the actual power consumed. Due to the coefficient of energy efficiency, when buying a source we will have to multiply the watts that the source is consuming to obtain the power supplied to our equipment. Good power supplies are at 80% or higher, where the remaining 20% dissipates in the form of heat or energy for which we are paying on our electricity bill for nothing more than fattening the electricity bills.
Buying a more efficient power supply serves to reduce the electrical consumption of our homes. For example, if we spend hours playing and our team demands 350 W, we are actually paying for 450 W, 100 W more expensive hour that at the end of the year can translate to more than 22 euros (depending on the hours we are in front of computer). The calculations I have made are 4KW of consumption more per week (about 4 or 5 hours a day in front of the computer), for 0.15 euros per KW, and for 52 weeks. If you are one of those who spend the day playing, what you are wasting money for a source of low efficiency I prefer not to calculate it.
There is none that reaches 100%, and you have to take it into account when buying so that we are not deceived. If you see a power supply of 20 euros with an efficiency of 90%, run away from it. Good and expensive power supplies reach 90% efficiency, some around 95% at half load, but none reaches more than 90 or 91% at full load. And these are nothing cheap -more than 100 euros for 700 W- .
Another important feature for their operation is whether they are active or passive PFC (Power Factor Correction) . It is simply another indication of its efficiency, since the passive usually give around half of its nominal power – with which half of the power consumed is lost in the form of heat , consuming more than the due, produce more environmental and electrical noise, and generally does not compensate for how little they cost.
Passive PFC sources generally do not have protections for the electronic components to which they have to feed, so in areas with constant blackouts are a danger to our pockets. In addition, having such a reduced efficiency, the electric bill at the end of the year can rise another 10 to 20 euros because of it, so I recommend that you do not put your eye on any of them and that you invest in an active PFC.
How much power do you need?
That is why it is advisable to take into account the area in which we live, the intense use (or not) that we are going to give, and calculate from there the power we need. For a team in which we play for a few hours in a hot summer area (almost anywhere in Spain), we usually consume about 350 to 400 watts in full load (ie, playing Battlefield 4 and similar games, or performing 3D design).
With a source of efficiency 80% (recommendable), and taking into account the geographical situation, in summer we could need a source of at least 600 W to compensate for its loss of efficiency, with an absolute minimum of 550 W. There will be cards that consume 150 to 200 W at full load that will need power supplies between 550 to 600 W.
Also the wear produced by the use will reduce with time its efficiency, besides that when a source provides between 40 and 60% of its maximum capacity is when it is more efficient. That is why it is advisable to increase the margin of watts that we think we need to not spend 60 euros in one and have to change it a year. Ideally, keeping it running at half its capacity maximizes its efficiency and at the same time its useful life.
Finally, and to make it clear, a source of 500 W and 80% efficiency is able to provide those 500 W but with a real consumption of about 620 W. If for example you calculate that your equipment consumes 450 W maximum , nothing prevents you from buying a 450 W power supply with 80% efficiency. It will give you those 450 W, but the problem comes from consumer peaks that exceed those 450 W (on the graphics cards are common) that negatively affect the components. This again means that the life expectancy of the source is greatly reduced and, as I say, we will pay more at the end of the month for electricity.
Operating below its limit also allows the source to generate less heat, for the fan to run at less revs and less to hear. The heat generated from operating at maximum load is also detrimental to the components, and decreases their life expectancy.