Picking The Right Power Supply: What You Should Know

The Power Window Is Important

Pegging Idle And Load Power Usage

Let us examine the characteristics of three typical usage scenarios. Now, we know that many mechanisms and techniques can help to reduce power consumption when the system has nothing to do. This is especially true for very powerful systems. That also means that the range of power levels at which they operate increases as well. In other words, they are quite frugal at idle and very demanding under full load. This so-called power window allows us to better define a system's individual requirements.

To illustrate the next part of the analysis, we are using four PSUs as examples. These include a cheap, high-powered model from the bargain bin (the purple line), an 80 PLUS-certified PSU (blue), another 80 PLUS Bronze model (orange-brown), and finally an 80 PLUS Gold option (yellow), capable of delivering between 500 and 525 W.

In the case of our super-cheap power supply, we decided to use a 750 W model to ensure that it’d be able to actually reach 500 W. Now when we take a look at their respective efficiency curves in a given scenario, we can see some pretty obvious (and unpleasant) differences:

As we can see, simply buying an efficient 500 W power supply is not a one-stop solution. To the contrary, these graphs should help us appreciate that choosing the right “size” power supply is at least as important as its quality and efficiency. You can only achieve an optimal result when all three factors are taken into consideration.