Will PSU fit in my case? [Read this First Before Buying]

Written By Steven Arends

You want to get a new power supply and you are wondering if you can use your existing case with the new PSU.

Or maybe you want to get a new case because the old one doesn’t look nice anymore.


Will PSU fit in my case?

Any standard ATX 12V PSU will fit in any standard power supply case. Some PSUs with more power, on the other hand, may be longer than a typical ATX PSU. The easiest method is to measure the PSU dimensions yourself and compare them with the case dimensions.

Don’t worry, as a tech enthusiast, who has spent his entire life assembling PCs all his life, I will provide a straightforward explanation on this topic. I have spent over ten hours finding the answers to all your questions.

So, grab yourself some coffee and stick with me till the end to clear up all your confusion.

Can an ATX PSU fit in a mATX case?

No, ATX PSU cannot fit in a mATX case. It’s possible to put mATX in an ATX case but not the opposite. The board compartment in an mATX case is only tall enough for a micro ATX motherboard, so a full ATX motherboard simply wouldn’t fit into the case.


I recommend you to get a case that was made for the type of PSU that you have. For instance, if you have a mini ATX power supply, you can get an mATX case or an ATX case or if you have an ATX power supply, you should get an ATX case.

That being said, there are a few mini ATX power supply cases that support some ATX power supplies and if there is any kind of support, it will typically be written on the box or on their website.

Moreover, mini ATX power supply cases can usually only fit ATX power supplies that have 4 mounting holes at most.

You can also take the measurements of your power supply and compare them to the case. If you do this, keep in mind that the case should be a little bit bigger to have a good amount of space for the cables.

Also, check our exclusive tutorial on how to use a PSU shroud.

How to check compatibility between your PSU and Case?

The first way is to take measurements of your PSU and compare it with the measurements of the case but you can use the pcpartpicker website to check compatibility too.

Here are the steps to check PSU compatibility:

  • Go to pcpartpicker website and type in your PSU make and model.
  • Select the PSU that matches yours from the search results.
  • Scroll down and look for Compatible Parts.
  • Click on the search field and search for the case.
  • Wait a couple of seconds and if it is compatible, it will show up in the search results. Otherwise, there will be no search results.

Do all PSU fit all cases?

Most ATX cases will fit perfectly with almost all cases. As long as your PSU has the standard dimensions, 150 × 86 × 140 mm, it will fit into any standard case. However, you might face an issue if you have a slim case since it’s not compatible with all the power supplies. Also, check out our separate post on why to use PSU shroud.

However, some exceptions like the Antec CP series, have a different width and height than the standard one so they require a special case.

Otherwise, if you have a normal tower case instead. It will fit any standard power supply.

The dimension that you should check is the depth or length of the power supply. This will show how far the PSU extends from the back panel to the case.

Does the PSU need to be in the case?

No, it’s perfectly fine if you use a PSU without a cover. However, your power supply would actually heat up much quicker if it’s used without a case. The cover directs the hot air from the PSU out which keeps the PSU cool.

Without a cover, the internal components of a power supply would just get hotter because of the lack of airflow.

Another point to consider is that if you use a power supply without a case, you will need to take extra care to not spill, trip, or drop something metallic on the PSU.

Have some time to spare? Quickly check out our epic guide on do modular PSUs come with cables.

Will an SFX power supply work in an ATX case?

While generally, SFX power supplies can fit inside a standard ATX case, but how well the SFX PSU fits comes down to what the case recommends or supports. You will probably need an adaptor that will enable it to screw in like a normal PSU.

SFX is for cases with a small form factor, while ATX is for regular ones.

If your case is a big ATX case, versus an ITX one, you should be able to fit anything in there.

Moreover, if it is indeed a smaller case, it should slot in without an adaptor as those are what these types of PSU are made for.

However, one thing to note here is that SFX power supplies typically always have shorter cable lengths. Therefore, you will probably need cable extensions for it to properly work inside an ATX case.

You might only need extra cable length for just a few of the components but it’s worth checking out before committing to your build completely.


Question: Will today’s PSU fit inside an older ATX case?

Answer: Yes, as long as the power supply is standard size. The standard size is 150 × 86 × 140 millimeters. If the PSU is bigger than this, you will need to look for a special case.

Question: Should I buy a case with a PSU?

Answer: No, because the power supplies included are usually of poor quality. Sometimes, the cover itself is of poor quality as well. I recommend to first research to find out whether the PSU included is worth it or not.

Question: Can micro ATX fit in Mid Tower?

Answer: Both the full-tower and mid-tower cases are able to fit standard ATX motherboards. They can also fit smaller micro-ATX motherboards. Most mid-tower cases run up to roughly 18 inches high and 8 or so inches wide but it still varies case to case.

Question: What size is an SFX PSU?

Answer: The standard dimension for this form factor is 125 x 63.5 x 100 millimeters. The fan size is also limited to 80mm. For small form factor enthusiasts, the standard SFX power supply form factor is the perfect combination of size and power.

Final Thoughts

I really hope I was able to empty your mind of all doubts and now I’m sure you are able to tell whether your PSU would fit your case or not.

If your PSU is not too special, it will fit any general case but if you have a power supply with a wattage that’s higher than most PSUs, then you will have to compare the measurements of the case with the length of the PSU to make sure they fit.

About The Author
Steven Arends is a computer science graduate and tech enthusiast with over 10 years of experience in the field. He has a vast collection of computer hardware and loves exploring the latest advancements. As a contributing author to 10Scopes, Steven shares his expertise to make the world of technology more accessible and easier to understand for all readers.

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