Choosing the Right Case
As motherboards, CPU coolers, power supplies and storage drives come in all shapes & sizes too, it is important to choose a case that not only suits your style but also comfortably fits the components you want and allows for future expandability too, if required. This guide walks you through the key considerations when choosing a PC case.
Motherboard Compatibility
The first and most important decision to get right is choosing a case that is big enough to house the motherboard. The good news is that whatever brand of case or motherboard you look at, all manufacturers design their components according to a common set of industry standards. All you need to do is ensure that the case and motherboard are both the same standard. The most common standard for mid-tower and full tower size PCs is ATX. The other standards are Micro-ATX and Mini-ITX, both of which are smaller than ATX, and finally the enormous E-ATX SSI-EEB standard. The diagram below illustrates the dimensions of the most common motherboard sizes.
| MINI-ITX | MICRO-ATX | ATX | E-ATX SSI-EEB | |
|---|---|---|---|---|
| Dimensions | 170 x 170 mm | 244 x 244 mm | 305 x 244 mm | 305 x 330 mm |
| Typical PCIe Slots | 1 | 4 | 7 | 7 |
| Typical DIMM Slots | 2 | 4 | 4 | 4+ |
Although a larger motherboard will require a larger case, there’s nothing to stop you installing a small motherboard in an oversized case. This could be beneficial as larger cases do provide some benefits such as more cooling options and additional drive bays. It all depends on how much space you have available for your PC and your other requirements.
PSU Compatibility
It’s also important to make sure you choose a case that is right for your PSU. Like motherboards, PSUs come in a variety of standard sizes as shown below.
Please note, there is no standard for micro-ATX PSUs, so a micro-ATX case will normally use an ATX PSU. One word of caution, some extremely high wattage PSUs, 1200W and above, are much longer than the 140mm of the ATX standard and so many require a case with an extra-long PSU bay. If in doubt check the Specification tab on the product page of the case on the Scan website.
ATX
SFX
TFX
Graphics Card Compatibility
High-end graphics cards, particularly those from the NVIDIA GeForce RTX 40-series onwards, are much larger than their predecessors, so its important to check that your graphics card will fit inside the case you're looking at, especially for smaller cases that are Micro-ATX and Mini-ITX.
You'll be able to find the dimensions in mm and the number of expansion card slots required in the Specifications tab of all graphics cards and cases on the Scan website.
If you want to add real stand-out to your PC, some cases enable you to mount the graphics card vertically rather than its usual horizontal configuration. Check out the photos below of two gaming PCs built by our 3XS Systems team inside the NZXT H9 Flow case, first with a traditional horizontal graphics card and below it with a vertical graphics card.
Horizontal Mount
In a traditional horizontal mount, your graphics card sits parallel to the motherboard, which is the standard configuration for most PC builds. This positioning allows for optimal airflow around the card, as cool air from front intake fans can flow directly across the GPU cooler and out through the rear exhaust fans. Horizontal mounting is the recommended setup for high-end graphics cards, especially those with vapour chamber coolers, as it maximises cooling efficiency and maintains peak performance temperatures.
The horizontal mount configuration also makes installation straightforward - the graphics card slots directly into a PCIe slot on the motherboard with no additional hardware required beyond the card itself. This is the most common and easiest mounting method, making it ideal for first-time builders. The main advantage is superior thermals, which means your graphics card will run cooler and quieter, allowing for better sustained performance during demanding gaming sessions or creative workflows.
Vertical Mount
Just beware that vertically mounting a graphics card will increase its temperature, reducing performance, especially for high-end graphics cards with vapour chamber coolers. To minimise this impact, try and use a smaller graphics card so there is more room for air to flow around it in the case, or as shown in these two PCs watercool the graphics card.
Depending on case design, mounting the graphics card vertically could be as simple as unscrewing and rotating the PCIe bracket. Alternatively, you may need to buy a vertical graphics card mounting kit which includes a new PCIe bracket. Either way, you'll also need a PCIe riser cable that will sit between the graphics card and motherboard as the former will no longer be slotted directly in the latter. For best performance and compatibility make sure to use a riser cable that is the same PCIe version as your graphics card and motherboard.
PCIe Riser Cable for Vertical Mount
PCIe Extension Cable for Vertical Mount
Cooling Capabilities
A well-designed case does a lot more than keep dust away from your precious PC components. It will also channel air through your PC, keeping everything cool and quiet - much better than having a PC sat out in the open. While every case is designed to air-cool a PC, some cases have additional fan mounts and space inside making them more suitable for watercooled PCs. Depending on your how you intend to cool your PC this is what you need to look out for.
The Best Cases for Air Cooling
Even the cheapest case will include a fan mount or two and normally some fans. If you’re building an entry-level PC a single exhaust fan at the back or top of the case is normally sufficient, but high-end PCs will require more fans, with some sucking cool air into the case and others exhausting hot air out of the case. Make sure you choose a case with sufficient fan mounts, ideally for 120 or 140mm fans as these are more efficient than smaller fans. Most manufacturers list on their product pages how many fans the case supports.
If you’re intending on using a particularly large CPU heatsink then make sure the case has sufficient space to house the cooler. Our product pages list the height on the ’Specifications’ tab so you can check against the width of any case. Always leave room to spare as some of the width of the case will be taken up by the motherboard and its standoffs.
Read our air-cooling buyers guide for further information on what else to consider.
The Best Cases for Hydrocoolers
If you’re going to buy a CPU or GPU with an all-in-one hydrocooler it’s critical you choose a case that has the right number of compatible radiator mounts. Hydrocoolers come in three main size groups, 120/140mm hydrocoolers with a single fan, 240/280mm hydrocoolers with two fans and 360/420mm hydrocoolers with three fans. You can check on our case product pages under the ’Specifications’ tab where it will be listed what size radiators the case supports.
Read our hydrocooling buyers guide for further information on what else to consider.
The Best Cases for Custom Water-Cooled PCs
Custom water-cooling is lot more complex than a CPU or GPU hydrocooler because you not only need to find a case that has the right number of compatible radiator mounts but also plenty of room for the pump, reservoir and tubing. Some cases provide dedicated mounting points for these components, but often your only option is to bolt or screw the pump and reservoir into any spare space you can find. For custom watercooled PCs the larger the case the better as it’ll have more space for the components and be easier to work inside while you’re building your custom watercooled PC.
Read our watercooling buyers guide for further information on what else to consider.
Drive Bays
SSDs and HDDs come in a number of form factors - M.2, 2.5in and 3.5in. While M.2 drives connect directly to the motherboard so require no bay, 2.5in and 3.5in drives will need a free bay inside the case, so its important to check the type and number of drive bays in any case you're considering.
It is also possible to use larger unused drive bays for smaller drives using adapters, for example you can get 3.5in to 2.5in adaptors. If you still want to use older storage formats such as CD, DVD or media cards, you will need to use an external USB device unless you opt for a case with a 5.25in external bay - probably hard to find these days.
Connectivity
In addition to the usual power and reset button, all PC cases have some external ports to help you connect devices to it, such as keyboards, mice, cameras and external drives. Some of these may be front mounted and some may be at the rear of the case.
The most popular combination is a mixture of USB Type A and C ports, plus 3.5mm minijack sockets for headsets or speakers.
Aesthetics
PC cases are available in a huge variety of colours, and many also have one or more transparent panels so you can showcase the hardware inside. At the cheaper end of the market these transparent panels are made from acrylic, but at the higher end they are made from tempered glass - we strongly recommend choosing a glass version as it much harder wearing and less susceptible to scratches.
If you want a case with a side window it’s worth thinking about orientation. The vast majority of mid tower and full tower PC cases are designed to be viewed from the left side panel, as they mount the motherboard on the right side of the case. If your desk arrangement is such that you can only have the PC on your left it’s important to choose a reverse case which mounts the motherboard on the left and has the window on the right. A tiny number of cases even allow you to choose the motherboard orientation yourself.
It is also worth mentioning that many cases also include RGB fans as standard, though you can always add more RGB fans and lighting strips according to your own tastes.
Minimising Noise
While every case will muffle the sound of your PC fans to some extent, some cases are specifically engineered to keep noise to a minimum. These cases are fitted a layer of foam on the outer panels that absorbs sound vibrations and plates to cover up unneeded fan mounts. Just beware that you need to strike the right balance between making your PC as quiet as possible while ensuring it is adequately cooled.
Some cases also include fan controllers with a dial or switch on the front panel to adjust fan speed. However, we’d recommend avoiding these in favour of using motherboard BIOS settings or a Windows application such as Corsair iCUE, to control the fan speed instead, as you’ll get far more control and can create a custom profile unique to your PC.
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Frequently Asked Questions FAQ
Here are some common questions and answers to help you find the information you need.
Absolutely, even an entry-level PC will require at least one fan to exhaust hot air out of the case. See the section on Cooling Capabilities for more information on how to configure the fans for optimum cooling.
This depends on a number of a factors:
- The size of your motherboard (Mini-ITX, Micro-ATX, ATX or E-ATX SSI-EEB).
- The size of your PSU (ATX, SFX, or TFX).
- The size of your graphics card.
- The number of fans required; the more high-end the components the more fans you'll need to keep everything cool.
- The number of 2.5 and 3.5in drive bays.
This buyers guide has detailed guidance on each of these five topics, plus lots more.
Motherboards come in four main form factors (Mini-ITX, Micro-ATX, ATX or E-ATX SSI-EEB), so you need to choose a case that supports one of these. You can find what form factor your motherboard is on the Specifications tab of the product page on the Scan website, the manufacturers website or the specifications section of the manual.
PC cases come in all shapes and sizes and are made from a wide variety of materials. Generally speaking, if you want the best airflow look for a case with a grille rather than solid front and top panels. See the section on Cooling Capabilities for more information on how to configure the fans for optimum cooling.
Many PC cases are available in a variety of colours, and you can of course also add RGB lighting and fans to any case.
If you'd like a customised case, unique to you, we also provide a case customisation service where our 3XS Systems team can paint your case any colour you like and/or etch your name or an image on it. You'll find these options on any PC configurator on the 3XS Systems website.
Alternatively, we can hand craft a totally unique system in any shape, size, colour or materials you want. Visit our 3XS Custom Shop to see how previous examples of custom-built PCs for inspiration.