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6 Questions to Ask Before Replacing a Power Supply

on October 13, 2022

6 questions to ask before replacing your power supply.

Is my Power Supply really dead?

So you’re not getting any video and your fans aren’t spinning on? More than likely, there is an issue with your power supply. There are a couple of ways to test a power supply. One way is to use a voltage meter. The other is to use a power supply tester. It’s a handy tool to have, especially if you’re a computer technician. The other way to check is to plug in a known good power supply into your motherboard. If your motherboard then boots, that means your power supply is bad.

What form factor PSU do I need?

There are several form factors power supplies come in including ATX, micro ATX, mini ITX, Micro PS3, LPX, SFX, WTX, CFX, and TFX. You can find a wide assortment. You can use the following information as a guide to choose the correct power supply for your chassis. Approximate dimensions for each are stated below:

ATX: 150 x 140 x 86 (mm)
Micro ATX: 126 x 101x 65 (mm)
Mini ITX/Flex: 160 x 140 x 85 (mm)
Micro PS3: 150 x 101 x 86 (mm)
LPX: 150 x 140 x 86 (mm)
SFX: 100 x 125 x 75 (mm)
WTX: 150 x 230 x 86 (mm)
CFX:  125 x 101 x 69 (mm)
TFX: 171 x 86 x 66 (mm)

May OEM manufacturers such has Dell, HP, and Lenovo use propriety version of the above form factors that may be different shapes, include rewiring, or proprietary connectors and wiring. For these PC's you must match up with the OEM or a replacement that was specially designed to fit your system.

How many watts do I need?

The more watts you have, the more devices your power supply can support which means you can add the latest graphics cards, the faster processors, additional hard drives, the works! Take special note to determine if your power supply is rated at true wattage or maximum wattage. A higher wattage does not necessarily mean that your power supply outputs more watts if it is rated at maximum power. True wattage is a more accurate rating of your power supply.

Can my power supply ever have too many watts?

Absolutely not! The power supply only outputs as many watts as is needed to power the installed devices in your computer. For example, let’s say you have a 480 Watt power supply. If the devices in your computer require 180 Watts, then that 480 Watt power supply will only output 180 Watts. The advantage of having the 480 Watt is that it can supply the 180 Watts while not being pushed to its maximum capability. This can lead to a longer lifespan for the PSU.


Should I buy a modular power supply?

A modular power supply is really a preference and can really clean up the look of your build. This is absolutely not required to have a good power supply. However, if you are a computer guru that wants minimal cables visible, the modular is the way to go! Modular typically is only available for higher end ATX form factor power supplies from brands such as EVGA or Corsair. These units come with an assortment of cables which you can choose to plug in the exact amount of cables you need for the devices rather than a bundle of cables that comes with most standard power supplies that are not removable. These PSU's typically come with nicer looking sleeved type for the sleek look. 

What's the best brand?

The better brands may cost more, but there is no one brand that makes the best power supply. For many, it depends on personal preference or their own experiences. Antec, Seasonic, Thermaltake, EVGA, and Corsair are a few of the big players in the higher-end power supply market. You’ll notice that the higher-end power supplies are generally heavier, due the amount and quality of products used in manufacturing the parts. That does not mean that a heavier power supply will always be a better power supply, but generally you will find weight and quality to have a direct correlation to each other. The better power supplies have an efficiency rating of 80 percent or above.

Ready to start? Check out our power supply section.