What determines the input power of a power supply?

We all know that there is such a nameplate on the PC power supply, and the corresponding rated power is also marked on it. Therefore, some users will take it for granted that the rated power on the PC power supply has the same definition as the rated power on other household appliances, which means The power consumption of the power supply during operation. The higher the rated power, the more power the power supply needs to consume. In this way, they also take it for granted that the 850W power supply consumes more power than the 550W power supply. Most electrical appliances in the home are marked with rated power. For example, a rice cooker with a capacity of 4L will be marked with "rated power 770W" on its nameplate, which means that when it is running at full power, it consumes 770W of power. Other electrical appliances such as refrigerators, air conditioners, televisions, etc. will also have similar labels, which basically refer to the power consumption required by the corresponding product when operating at full power.

But in fact, the power rating of a PC power supply is by definition different from the power rating of most household appliances. The rated power on household appliances actually refers to the "rated input power", which generally refers to the power consumption when the workload is the highest; while the rated power on the PC power supply refers to the "rated output power", just like a battery, it represents It is the ability to supply external power. In other words, these two "rated powers" are not the same parameters at all and have no direct comparison value.

Of course, according to the law of conservation of energy, if the PC power supply needs to output 850W power, it must also input at least 850W power. According to this calculation, the power consumption of the 850W power supply will still be higher than that of the 550W power supply. However, the real situation is definitely not like this. A power supply with a rated power of 850W does not mean that it will always output 850W power when working. In fact, the output power of the power supply is dynamic and will depend on the hardware connected to it and the tasks it is running. However, the "rated power" only determines its output upper limit and does not represent its actual output level.

Therefore, whether you are using an 850W power supply or a 550W power supply, as long as the hardware connected to the power supply does not change and the running load does not change, the actual power output from the 850W power supply and the 550W power supply will be the same, and it will not change because of Changes occur due to changes in power supply.

What other factors affect the input power of the power supply?

However, the PC power supply is ultimately an AC-DC converter. Before superconducting technology can be conventionalized and popularized, such a converter will inevitably cause energy loss. When the power output is 400W, the input power will inevitably be greater than 400W. Therefore, in addition to the hardware and running load, there is another important factor that determines the actual input power of the PC power supply, which is the conversion efficiency of the power supply.

The conversion efficiency of a PC power supply refers to the ratio between the input power and the output power of the power supply, which is generally described in the form of a percentage. The conversion efficiency of different power supplies is different, and the conversion efficiency is not a fixed number. It will behave differently depending on the output power of the power supply. According to the definition of conversion efficiency, the output power of the power supply = input power x conversion efficiency. In other words, when the output power remains unchanged, the higher the conversion efficiency, the lower the input power, and the more power the power supply naturally saves.

Let’s take ROG Snow Eagle 850W and Xianma Gold 500W Gold Power Supply as examples. These two power supplies are both 80Plus Gold certified products. When the output power is 100W, the conversion efficiency of ROG Snow Eagle 850W power supply is 88%, while The Xianma Gold 500W gold version is 89%, and the latter will save more power at this time; but when the output power is 400W, the conversion efficiency of the former can reach 94%, and the latter is around 92%. At this time, ROG Snow Eagle 850W is even better in terms of power saving.

Therefore, we cannot generally judge whether a high-power power supply or a low-power power supply saves more power in actual use. Whether an 850W power supply or a 550W power supply should be used is not a decisive factor, but the power consumption level of the hardware. is the key to determining what power source you need. Only after the power supply needs of the hardware are met, is it time to consider secondary conditions such as electrical performance and power saving.

This is why we prefer high-power power supplies, because high-power power supplies have sufficient margin to cope with different platforms and can easily meet the needs of different platforms. Of course, the price of high-power power supplies will indeed be relatively high, and even for power supplies of the same power, products from different manufacturers will have different electrical performance, making it difficult for players to directly judge the performance of the power supply. Therefore, in this case, we recommend that players follow the following criteria to choose a power supply that suits them.