When talking about power supplies, there are two types of ratings used to measure its efficiency, continuous, and peak ratings. The continuous rating is what consumers see when they look at the rating that is printed by the manufacturer on the label. This is the manufacturer’s claim of how efficient that power supply is when running for a continuous amount of time. The peak power rating is the efficiency of the power supply when at peak draw. This is when the computer is working at its maximum and is almost always during startup. For most computers, the +12 voltage that is provided by the power supply is used mostly to rotate the disk motors. During startup, these disks can take up to twice their steady state current. If you have multiple disks in your computer system, this can create a tremendous demand for your power supply to maintain a +12 V power.
Both the peak rating and the continuous power rating should be printed on the label of the power supply. Most power supply companies build the ability for the power supplies to run over their normal output for short amounts of time like startup. The issue is not a big for power supplies that are only +3.3 or +5 voltages so you will not always see a peak rating on these low voltage power supplies.
You need to keep in mind that, although power supplies can run over their normal output, that this does not mean you should overload your system to its maximum. You can also delay the startup of one or more disks if you are operating with more than 4. This will spread the amount of maximum power being drawn out over time so that not every disk is drawing the +12 voltage at the same time.
Another way you can improve the amount of power being used and make sure it is being used efficiently is by running the DriverAssist program on your personal computer. This program is part of maintaining your total system health and should be allowed to run automatically. When manufacturers release new drivers for programs on your computer, or your computer itself, they are released onto the internet and need to be downloaded. DriverAssist scans your computer and review all the drivers on the internet to see if you have the latest and newest versions. Once the program completes the scan, you can see all the drivers that it found and select which ones to download. Typically, you should download and install all the new drivers that DriverAssist finds because they will keep your programs and applications current. This will help in the overall efficiency of your computer, especially during start up where programs are loading and running in the background.
If you are building a computer from scratch and upgrading different components, considering upgrading your power supply to handle a more demanding startup will be a very good idea. If you know you will be adding multiple disks soon or over time, your power supply should be upgraded first.