Computer case specs: what to look for before you buy

The form factor label describes what the case is built to hold, and it sets everything downstream. A full tower gives you room for an E-ATX board, a long graphics card and a large custom loop, at the cost of desk space and weight. A mid tower is the sensible default for most builds. A mini tower or small form factor case trades clearance for footprint, and the trade is real: the smaller the box, the more precisely every part has to be chosen.

Volume in litres is the number to compare rather than the marketing label, because "mini tower" spans everything from about 20 to 30 litres. Below roughly 20 litres you are into genuine small form factor territory, where the power supply may have to be an SFX unit and the cooler height limit starts to bite. Decide the volume you can live with before you fall in love with a particular case.

Cases are listed by the biggest motherboard they accept, and a case that takes E-ATX will also take ATX, Micro-ATX and Mini-ITX. Buying above your board size costs nothing in compatibility but does cost space and money, so match the case to the board you actually plan to use.

Watch for width limits rather than just the standard name. An E-ATX board can be anywhere from 305 to 330mm wide, and some cases quote only the narrower figure. If you are reusing a workstation or high-end board, measure it and compare against the published maximum. Expansion slot count usually tracks the board size too, so a Micro-ATX case with four slots is telling you something about the boards it expects.

Graphics card length is the single most common reason a build does not fit. Modern triple-fan cards run from about 300mm to well over 350mm, and the clearance a case quotes is usually measured with the front fans installed and no radiator. Fit a front radiator and you lose 25 to 30mm, which is enough to turn a comfortable fit into a no.

Check the card's exact length on the manufacturer's page, not the retailer listing, and check the case figure in the same configuration you plan to build. Width matters too: a card thicker than about three slots can foul a side-mounted fan bracket or a glass panel in a narrow case. Depth, width and height all have to pass, not just depth.

Air coolers are quoted by height, and a case that clears 160mm will not take a 170mm tower. Large dual-tower coolers sit around 155 to 170mm, and the tallest reach beyond that. The quoted figure is measured from the motherboard surface to the side panel, so it shrinks if you add a side-mounted fan bracket or a particularly thick panel.

If you plan to use a 360mm all-in-one liquid cooler instead, height matters far less and radiator clearance takes over. Either way, decide the cooling solution before the case, because it is much easier to pick a chassis around a known cooler than to buy a cooler that fits a chassis you already own.

Liquid cooling support is quoted as a list of positions and sizes: front 360, top 240, rear 120 and so on. Read it as a set of mutually exclusive options. A case that lists a 360mm front and a 240mm top usually means you can have one or the other at full size, not both, and the manual will spell out the combinations that actually fit.

Radiator thickness matters as much as length. A 30mm radiator plus 25mm fans needs 55mm of clearance, and push-pull configurations need roughly twice that. Top-mounted radiators compete with motherboard VRM heatsinks and tall memory, which is why some cases quote a reduced radiator size only with low-profile RAM. Check the manual's clearance diagram before buying a thick radiator.

Two cases with identical dimensions can run ten degrees apart. What separates them is how freely air enters and leaves. A mesh front, mesh top and mesh bottom give the fans something to work with; a solid glass front turns the same fans into noise generators. Look at the gap between the front panel and the fan mounts, because a mesh panel pressed flat against the fans is barely better than a solid one.

Count the fan mounts and note which sizes they take. Three 120mm front intakes move more air at lower noise than two 140mm, and a bottom intake directly under the graphics card helps more than an extra exhaust at the rear. Cases that ship with fans save money but check which ones: a case bundling three ARGB fans is often better value than a bare chassis once you price the fans separately.

Drive bays are disappearing, and for most builds that is fine: one or two M.2 drives on the motherboard cover everything. Physical bays still matter for bulk storage, for reusing old drives, and for a 5.25 inch optical or hot-swap bay, which is now a genuinely rare feature.

Check whether the 3.5 inch mounts are dedicated or shared with 2.5 inch drives, because shared mounts mean you cannot use both at once. Also check where they sit: a 3.5 inch cage in the front intake blocks airflow to the graphics card unless it is removable. If you keep a media library, buy for the bays you will fill in two years rather than the ones you need on day one.

Front panel connectivity is usually an afterthought until you need it. The important questions are whether there is a USB-C port, what speed it runs at, and whether the case's front panel uses a replaceable cable. A USB-C port running at 5Gbps is common on budget cases and is fine for a keyboard or a phone; the 10Gbps and 20Gbps versions matter for external SSDs and card readers.

Check the audio jack too, and whether it is a combined headphone and microphone socket or two separate ones. On a case with a card reader, fan controller or LCD display, the front panel also needs internal power and data connections, which is another cable to route. Fewer, faster ports beat a row of slow ones.

At the bottom of the market a case is steel, plastic and acrylic. Move up and the acrylic becomes tempered glass, the plastic becomes powder-coated steel, and the front panel may become real wood or aluminium. None of that changes performance much, but it changes how the build looks and how long it lasts, and a steel frame with 0.6mm panels flexes where a 1.0mm frame does not.

Glass thickness is worth noting: 3mm is the budget norm and 4mm looks clearer and feels more substantial. A 270 degree wrap-around glass panel shows off the build but hides almost no cable mess, so it only pays off if you plan to manage the cables properly. Mesh side panels cool better and hide more.

Case prices run from under $30 to several hundred, and the curve is steep at the bottom: the difference between a $25 case and a $70 case is much larger than between $70 and $150. The cheap end buys thinner steel, acrylic instead of glass, fewer included fans and shorter clearances, which is a real constraint if you plan a long graphics card.

Budget sensibly against the rest of the build. Spending $150 on a case for a $600 build is a poor allocation, and spending $30 on a case for a $2,000 build usually means fighting the chassis every time you open it. The sweet spot for most builds is roughly $70 to $110, where you get mesh, tempered glass, a USB-C front port and clearances that fit current hardware.