What Power Supply Do I Have?

Is “what power supply do I have” a question you’ve asked yourself when planning to upgrade your PC? Or when building a new one? Or at any other time?

Then you’re in the right place to find the answer. Unlike the GPU or the CPU, your PSU doesn’t interact with the motherboard in a way that it can relay information. Therefore it’s impossible to gauge the capabilities of your power supply with a software solution.

Power supply tends to get overshadowed by the more flashy components, but seeing how it’s the very thing that gives them power, I’d say it’s imperative to know about it. Knowing how much power you have is a must, especially if you’re building a PC on your own.

Of course, if you bought a pre-built PC, your power supply will likely be correctly optimized for the build, and you won’t have too many issues unless you’re planning to upgrade the pre-built PC. But that’s a whole different can of worms.

What you need to know is that there are two ways of figuring out what power supply you have, but they depend on your PC.

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Opening Up The Case

The most obvious method is to simply take a peek under the hood and read the declaration. As required by the UL (formerly Underwriters Laboratories), the PSU has to have a label with power rankings on it.

So, when you’ve opened up the case, you should easily locate the PSU and the sticker on it. However, it is possible that you won’t be able to find the sticker because they sometimes get placed on a different side of the PSU. If this is the case, you will have to open the back of the case and see if it’s there. And if it isn’t, then it likely isn’t at the top either.

What this means is that you won’t be able to know which PSU you have, and that is very dangerous. You can’t know if the current build is intended for this specific power range, and if upgrading it can lead to trouble. In this scenario, it’s recommended to get a new power supply unit as having that label is a safety requirement.

Understanding The Label Of The Power Supply Unit

So, you’re looking at the sticker with a table and a bunch of numbers on it and you’re probably confused. Don’t worry, here’s a quick guide on what it all means.

RM 850X - Understanding The Label Of The Power Supply Unit
Example Label – RM 850X
  • Wattage – Usually written with the biggest font and by some margin. Pretty much gives you the information you probably need the most.
  • PSU Name/Model – This will likely be written in a weird production code that you can put in your Google machine and learn more about the model, like what connectors does it have.
  • Input Voltage – Power Supply functions on AC voltage, and that is what you have to supply to it. For the US, Canada, and most South American countries, this number will be roughly around 110V – 127V, and for UK, Europe, Asia, Africa, and Australia, etc., it is 200 – 240V. This, of course, is in correlation to the power socket voltage.
  • DC Output – Conversely, this is the power that your PSU provides for your computer. Standard output voltages are +3.3V, +5V, +12V, and +5VSB. You may also find -12V, but that is no longer in use. These are also known as Rails, such as 3.3V Rail, 5V Rail, and so on.
    +5VSB is always on as it powers mouse, keyboard, memory, LAN, and BIOS memory to support the PC when it’s on standby mode.
  • Max Load or Max Current– Under each table cell for voltage, you’ll find the label for the maximum current load. You should know that this particular wording is sometimes omitted, but in most cases, you’ll find it directly under the corresponding voltage. Its unit is Ampere, and if you overload it, it may lead to a shutdown.
  • Maximum Power (Combined) – This will be directly under output cells and is calculated in Watts. This is the formula used in this calculation: Power (W) = Voltage (V) X Current (I)
  • Total Power – Some manufacturers only use the total combined power of 12V Rail as it powers 80-90% of the components, while others will calculate all the rails.

Searching The Manual Or Looking It Up Online

This is the best and easiest method to use when determining which power supply you have if you own a pre-built PC.

There’s no need to open up the case and potentially cause problems by being careless when there’s already a ready-made text to help you out. If your PC didn’t come with the manual, I hope you at least know what model it is. Then you can search it online and find the specifications on the manufacturer’s website.

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Aleksandar Cosic

Alex is a Computer Science student and a former game designer. That has enabled him to develop skills in critical thinking and fair analysis. As a CS student, Aleksandar has very in-depth technical knowledge about computers, and he also likes to stay current with new technologies.