The power supply is more powerful than needed. How to choose a power supply for your computer without making a common mistake
Many users, in pursuit of high performance of a personal computer, forget about the main element of the system unit, which is responsible for high-quality and timely provision of power to all components inside the case. We are talking about a power supply that buyers do not pay attention to at all. But in vain! After all, all elements in a computer have certain power requirements, failure to comply with which will lead to component failure.
From this article, the reader will learn how to choose a power supply for a computer, and at the same time get acquainted with products from well-known brands that are recognized by all test laboratories in the world. Advice for ordinary users and beginners, provided by experts in the field of IT technologies, will help all potential customers make their choice in the store.
Definition of need
Before starting to search for a decent power supply, all users need to decide on the power supply. That is, first the buyer must select the elements of the system unit (motherboard, processor, video card, memory, hard drives and other controllers). Each system component in its specification has power requirements (voltage and current, in rare cases - power consumption). Naturally, the buyer will have to find these parameters, add them up and save the result, which will be useful in the future.
It doesn’t matter what actions are carried out by the user: replacing the computer’s power supply or purchasing an element with a new PC - calculations must be carried out in any case. Some elements, such as the processor and video card, have two power requirements: active voltage and peak load. You need to focus your calculations on the maximum parameter.
Finger to the sky
There is a strong opinion that for a resource-intensive system you need to choose the most powerful power supply that is on the storefront. This decision has logic, but it does not fit in with rationality and saving money, because the higher the power of the device, the more expensive it is. You can buy a price that exceeds the cost of all elements of the system (30,000 rubles and more), but such a solution will be very expensive for the consumer in the future.
For some reason, many users forget about the monthly payment, which is necessary for the operation of a personal computer. Naturally, the more powerful the power supply, the more electricity it consumes. Thrifty buyers cannot do without calculations.
Standards and power losses
The bigger, the better
Many experts, in their advice on how to choose a power supply for a computer, recommend that all beginners pay attention to the number of connectors and cables - the more there are in the device, the more efficient and reliable the power supply system. There is logic in this, because manufacturing plants carry out testing before releasing products to the market. If the power of the unit is low, then there is no point in providing it with a large number of cables, because they will still be unused.
True, recently many careless manufacturers have resorted to a trick and provided the buyer with a large wire clamp in a low-quality device. Here you need to focus on other indicators of battery efficiency (weight, wall thickness, cooling system, presence of buttons, quality of connectors). By the way, before connecting the power supply to the computer, it is recommended to visually inspect all the contacts coming from the head unit and make sure that they do not intersect anywhere (we are talking about cheap representatives of the market).
Top seller
Seasonic, a company specializing in the production of batteries, is known throughout the world. This is one of the few brands on the market that sells its own products under its logo. For comparison: the well-known manufacturer of computer components - the company Corsair - does not have its own factories for the production of power supplies and purchases finished products from Seasonic, equipping them with its own logos. Therefore, before choosing a power supply for a computer, the user will have to become more familiar with the brands.
Seasonic, Chieftec, Thermaltake and Zalman have their own factories for the production of batteries. Products under the well-known FSP brand are assembled from spare parts produced at the Fractal Design plant (by the way, they have also recently appeared on the market).
Who to give preference to?
Gold-plated computer power supply connectors are good, but is there any point in overpaying for such functionality, since it is known for certain from the laws of physics that current is better transmitted between homogeneous metals? But it is Thermaltake that offers users such a solution. As for the rest of the products of the famous American brand, they are impeccable. There is not a single serious negative response from users about this manufacturer in the media.
The trusted products on the shelf include the brands Corsair, Aercool, FSP, Zalman, Seasonic, Be quiet, Chieftec (Gold series) and Fractal Design. By the way, in test laboratories, professionals and enthusiasts check the power and overclock the system with the power supplies listed above.
Finally
As practice shows, choosing a decent power supply for a personal computer is not easy. The fact is that many manufacturers use all sorts of tricks to attract buyers: they reduce the cost of production, decorate the device to the detriment of efficiency, and present a description that does not correspond to reality. There are many mechanisms of deception, it is impossible to list them all. Therefore, before choosing a power supply for a computer, the user must study the market, become familiar with all the characteristics of the device, and be sure to find positive reviews about the product from real owners.
Here is another informative article, this time on the topic of hardware. More precisely, about choosing the right power supply for your system. Most likely you will think that there is nothing complicated here, you just need to look at the power and choose the manufacturer. But no, this is the most common mistake of all novice users, since when you come home and start connecting a brand new power supply, you may be unpleasantly surprised when you realize that something doesn’t fit. And to avoid such mistakes, I strongly recommend that you read this article.
Let's start with the simplest thing, what is a power supply? A computer power supply is a voltage converter that supplies all computer components with direct current and the voltage required for each element. A modern power supply should provide voltages of 3.3V, 5V and 12V.
Power. One of the most important points when choosing a power supply, of course, is the correct selection of power. If you install a power supply with a weaker power than your system needs at peak load, this will result in system instability and a high probability of failure of some components. If you install a power supply of unreasonably higher power, this will affect its efficiency and increase power consumption. There are quite a few calculators on the web for calculating the power of power supplies, but I recommend using the Asus power calculator, since it is regularly updated and there are always new video cards and processors in its list. You can add 50W to the received power for reserve; I also recommend looking at a power supply not lower than the 80+ Bronze standard (you can read more about the 80 plus standard on wikipedia.org).
Firm. This is somewhat more complicated and it is necessary to seriously study each model, because, as with everything, some models are successful, some are not. Still, I strongly advise against contacting a noname power supply unit, but rather look towards such manufacturers as Thermaltake, Chieftec, Corsair. Personally, I have been buying components at the OGO.ru store for a long time, but first, read the article.
Wires and connectors. Let's move on to the most interesting part. It is precisely because of your inattention to this topic that the purchased power supply may not be suitable. If you pay attention to the characteristics of motherboards, you may notice that the specifications always indicate two important points:
1) Main power connector;
2) Processor power connector.
It is because of inattention to these two points that beginners have problems.
In modern motherboards, the 24-pin main power connector is most often found, but the processor power connector is divided into two types: 8-pin ...
On server motherboards there is also a 20-pin for the main power supply.
A universal option would be to purchase a power supply with a connector for the motherboard 20+4pin, and for the processor 4+4pin. This will allow you to connect this power supply to any motherboard. But for purely home use, you can often just take 24pin power for the motherboard.
Don’t forget about video cards, since if you have a powerful video card installed, then most likely it requires an additional 6-pin power supply, sometimes even 6+6pin. That is, two connectors of 6pin each. The number of hard drives and optical drives is also important, since all modern hard drives and drives are powered by a Sata connector. Although, if you have an old computer, then you should pay attention to IDE and Floppy connectors.
So, when choosing a power supply, the second most important thing is the selection of connectors suitable for your system unit assembly:
To summarize, we can say that you should carefully read the specifications of the motherboard and video card, look at the dimensions of the case and the location of the power supply in it so that the wires are long enough to reach all the elements. Plus, you can choose a power supply with detachable cables, this will free up some space in the case by disconnecting unnecessary wires.
PFC(Power factor Correction). Translated as “reactive power compensation”. I recommend choosing a power supply with Active PFC. This will reduce interference in the network, it will also stabilize the incoming voltage and the power supply will be much less sensitive to voltage drops. This essentially allows the power supply to be used in a universal voltage range of 110-230V.
PSU cooling. It is desirable that the fan be at least 120mm in diameter, but this condition is met in almost all power supplies.
That's all. You can safely go to the catalog of the OGO.ru online store and choose the power supply that suits you.
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Measurements of system energy consumption turned out to be quite expected. The simplest system without a discrete video card could probably get by with any compatible power supply at all. We can also see that the now quite old AMD Phenom II X4 965 processor shows a decent difference in power consumption when compared to the less demanding Intel Core i7-3770K. However, technically, all four systems would be able to function properly even on a 450 W power supply (of adequate quality with honest watts).
So who will need 1000 W power supplies then? Obviously, they can also find real use, for example, if you have a sophisticated gaming system worth about one hundred thousand rubles with three video cards. Some information storage enthusiasts have the weakness of installing about twenty hard drives with a bunch of additional controllers, but for most ordinary, even powerful systems, an honest (read: high-quality) 550 W power supply will be enough. An office computer without discrete video (or with entry-level devices) can probably get by with one of the lowest-power devices.
Conclusion
The results we received speak for themselves. Even a powerful gaming computer with overclocked components does not consume more than 360 W at peak. That is, it is obvious that you will not need a kilowatt power supply until you decide to assemble a 3-Way SLI configuration. Of course, the results should not mislead you. They do not mean at all that you can use a 400 W power supply from cases with a total cost of 900 rubles for such an assembly. But in the end, there is no reason to buy a really high-quality 750-1000 W power supply; you can get by with a cheaper and fairly reliable model that will work on your computer - and still with a large margin.
A power supply is a PC component that converts 220 V mains into the 3.3-12 V needed for various devices. And, alas, many people have no attitude towards choosing a power supply - they simply take it as change from the purchase of other components, often right away along with the body. However, if you are assembling something more powerful than a multimedia computer, then you should not do this - a bad power supply can easily damage expensive processors or video cards, and so that later, as in the saying, “the miser pays twice,” it is better to buy a good power supply right away.
Theory
First, let's figure out what voltage the power supply supplies. These are the 3.3, 5 and 12 volt lines:
- +3.3 V - designed to power the output stages of the system logic (and in general power the motherboard and RAM).
- +5 V - powers the logic of almost all PCI and IDE devices (including SATA devices).
- +12 V is the busiest line, it powers the processor and video card.
But the 12 V line is very busy - it powers both the processor (50-150 W) and the video card (up to 300 W), so the most important thing in the power supply is how many watts it can deliver through the 12 V line (and this By the way, the figure is usually close to the total power of the power supply).
The second thing you need to pay attention to is the power supply connectors - so that it doesn’t happen that the video card requires a couple of 6 pins, but the power supply only has one 8 pin. The main power supply (24 pin) is present on all power supplies, you can ignore this. Additional power supply for the CPU is presented in the form of 4, 8 or 2 x 8 pin - depending on the power of the processor and motherboard, respectively, make sure that the power supply has a cable with the required number of contacts (important - 8 pin for the video card and for the processor are different, do not try swap them!)
Next is additional power for the video card. Some low-end solutions (up to GTX 1050 Ti or RX 460) can be powered through the PCI-E slot (75 W) and do not need additional power. However, more powerful solutions may require from 6 pin to 2 x 8 pin - make sure that the power supply has them (for some power supplies, the contacts may look like 6+2 pin - this is normal, if you need 6 pin, then connect the main part with 6 contacts, if you need 8, add 2 more on a separate cable).
Peripherals and drives are powered either through a SATA connector or through Molex - there are no divisions into pins, just make sure that the power supply has as many necessary connectors as you have peripheral devices. In some cases, if the power supply does not have enough pins to power the video card, you can buy a Molex - 6 pin adapter. However, in modern power supplies this problem is quite rare, and Molex itself has almost disappeared from the market.
Form factors of power supplies are selected either for the case, or, conversely, if you have chosen a good power supply unit of a certain form factor, then you select the case and the motherboard to match it. The most common standard is ATX, which is what you'll most likely see. However, there are more compact SFX, TFX and CFX - these are suitable for those who want to create a very compact system.
The efficiency of a power supply is the ratio of useful work to expended energy. In the case of power supplies, their efficiency can be determined by the 80 Plus certificate - from Bronze to Platinum: for the first it is 85% at 50% load, for the latter it is already 94%. There is an opinion that a power supply with a 500 W 80 Plus Bronze certificate can actually deliver 500 x 0.85 = 425 W. This is not so - the unit will be able to deliver 500 W, but it will simply take 500 x (1/0.85) = 588 W from the network. That is, the better the certificate, the less you will have to pay for electricity and nothing more, and taking into account the fact that the difference in price between Bronze and Platinum can be 50%, there is no particular point in overpaying for the latter, saving on electricity will pay off oh so much not soon. On the other hand, most expensive power supplies are certified at least Gold, that is, you will be “forced” to save electricity. 
Power Factor Correction (PFC)
Modern units are becoming more powerful, but the wires in the sockets do not change. This leads to the occurrence of impulse noise - the power supply is also not a light bulb and, like the processor, consumes energy in impulses. The stronger and more uneven the load on the unit, the more interference it will release into the power grid. PFC was developed to combat this phenomenon.
This is a powerful choke installed after the rectifier before the filter capacitors. The first thing it does is limit the charging current of the aforementioned filters. When a unit without PFC is connected to the network, a characteristic click is often heard - the consumed current in the first milliseconds can be several times higher than the rated current and this leads to sparking in the switch. During computer operation, the PFC module dampens the same impulses from the charging of various capacitors inside the computer and the spin-up of the hard drive motors.
There are two versions of the modules – passive and active. The second is distinguished by the presence of a control circuit connected to the secondary (low-voltage) stage of the power supply. This allows you to react faster to interference and better smooth it out. Also, since there are quite a lot of powerful capacitors in the PFC circuit, an active PFC can “save” the computer from shutting down if the electricity goes out for a split second.
Calculation of the required power supply power
Now that the theory is over, let's move on to practice. First you need to calculate how much power all PC components will consume. The easiest way to do this is to use a special calculator - I recommend this one. You enter your processor, video card, data on RAM, disks, number of coolers, how many hours a day you use your PC, etc. into it, and in the end you get this diagram (I chose the option with i7-7700K + GTX 1080 Ti): 
As you can see, under load such a system consumes 480 W. On the 3.3 and 5 V line, as I said, the load is small - only 80 W, which is what even the simplest power supply will deliver. But on a 12 V line the load is already 400 W. Of course, you shouldn’t take a power supply back to back - 500 W. He will, of course, cope, but, firstly, in the future, if you want to upgrade your computer, the power supply may become a bottleneck, and secondly, at 100% load, the power supplies make a very loud noise. So it’s worth making a reserve of at least 100-150 W and taking power supplies starting from 650 W (they usually have 12 V lines output from 550 W).
But several nuances arise here:
- You shouldn’t save money and buy a 650 W power supply built into the case: they all come without PFC, that is, one voltage surge - and in the best case you go for a new power supply, and in the worst case, for other components (up to the processor and video card) . Further, the fact that 650 W is written on them does not mean that they will be able to deliver that much - a voltage that differs from the nominal value by no more than 5% (or even better - 3%) is considered normal, that is, if the power supply supplies 12 There is less than 11.6 V in the line - it is not worth taking. Alas, in noname power supplies built into the case, drawdowns at 100% load can be as high as 10%, and what’s even worse - they can produce a noticeably higher voltage, which may well kill the motherboard. So look for a PFC with active PFC and 80 Plus Bronze certification or better - this will ensure that there are good components inside.
- It may be written on the box with the video card that it requires a 400-600 W power supply, when it itself barely consumes 100, but the calculator gave me a total of 200 W under load - is it necessary to take a 600 W power supply? No, absolutely not. Companies that produce video cards play it safe and deliberately increase the requirements for power supplies so that even people with power supplies built into the case will most likely be able to play (since even the simplest 600 W power supply should not drain voltage under a load of 200 W).
- If you are putting together a quiet assembly, then it makes sense to take a power supply that is one and a half or even 2 times more powerful than what your system actually consumes - at 50% load, such a power supply may not turn on the cooler for cooling at all.
Measurements of system energy consumption turned out to be quite expected. The simplest system without a discrete video card could probably get by with any compatible power supply at all. We can also see that the now quite old AMD Phenom II X4 965 processor shows a decent difference in power consumption when compared to the less demanding Intel Core i7-3770K. However, technically, all four systems would be able to function properly even on a 450 W power supply (of adequate quality with honest watts).
So who will need 1000 W power supplies then? Obviously, they can also find real use, for example, if you have a sophisticated gaming system worth about one hundred thousand rubles with three video cards. Some information storage enthusiasts have the weakness of installing about twenty hard drives with a bunch of additional controllers, but for most ordinary, even powerful systems, an honest (read: high-quality) 550 W power supply will be enough. An office computer without discrete video (or with entry-level devices) can probably get by with one of the lowest-power devices.
Conclusion
The results we received speak for themselves. Even a powerful gaming computer with overclocked components does not consume more than 360 W at peak. That is, it is obvious that you will not need a kilowatt power supply until you decide to assemble a 3-Way SLI configuration. Of course, the results should not mislead you. They do not mean at all that you can use a 400 W power supply from cases with a total cost of 900 rubles for such an assembly. But in the end, there is no reason to buy a really high-quality 750-1000 W power supply; you can get by with a cheaper and fairly reliable model that will work on your computer - and still with a large margin.