Introduction and First Impressions

Another take on the Define R5 with advanced cooling capability.

The Define S from Fractal Design is a mid-tower enclosure based on the company’s excellent Define R5, and this version has a new interior for enhanced cooling support with an innovative approach to storage.


I've mentioned before that the PC enclosure market is crowded with options at every price point, but this can actually be a good thing because of the high level of individual preference this permits. Selecting a case is a multi-faceted thing, and while they all (well, mostly) keep components safely housed, once that need has been met there's a lot more to consider. Let's face it, aesthetics are important since the enclosure is the outward-facing representation of your build (and personal style). Support for your preferred type of cooling, storage, and future expandability are high on the list when selecting a finalist as well, and then there's the thermal/noise performance element to consider. It was Fractal Design's own Define R5 (review here) which offered a balanced approach to these needs, and while not looking especially flashy with understated style and a standard ATX layout, the R5 was an exceptionally well-done effort overall. Now, months later, enter the Define S.

With the Define R5 offering a solid combination of silence, expandability, and build quality, why would Fractal Design create another very similar case right on its heels? It’s all about giving people choice, and that’s something I can certainly stand behind – even when it means further segmenting a market that seems almost impossibly crowded now. And when we dive deeper into the Define S we see what is essentially a companion to the Define R5, and not a replacement. At first glance this might appear to be an identical case, but the interior layout clearly separates the two. In summary, the Define S loses 5.25” storage support found in the R5, and while that previous model had no less than 8 hard drive trays the S employs a novel approach to HDD support, but cuts the drive support from 8 standard 3.5" drives to just 3 in the process.

With these changes the interior is now completely open which allows for great flexibility for any kind of cooling setup, and water cooling in particular. A further dive into the custom cooling aspect of this case would make for an interesting second look at this enclosure, but for now we’ll check out a conventional build with an all-in-one liquid cooler setup.

First we'll check out specs from Fractal Design:


  • ATX, Micro ATX, Mini ITX motherboard compatibility
  • 7 expansion slots
  • 3 – 3.5" HDD positions (can also accommodate 2.5" units); 2 – 2.5" dedicated SSD/HDD unit positions
  • 9 – Fan positions (2 Fractal Design Dynamic GP14 140mm fans included); 8 fan positions on window model
  • Filtered fan slots in the front and bottom
  • CPU coolers up to 180mm in height
  • ATX PSUs up to 180/170 mm with a bottom 120/140mm fan installed; When not using any bottom fan location longer PSUs up to 300mm can be used
  • Graphics cards up to 425 mm in length with front fans installed, without compromising HDD capacity; Graphics cards up to 450mm in length without front fans installed directly in line with the GPU
  • With a front radiator, maximum graphics card length is reduced by the radiator thickness
  • 20 – 40 mm of space for cable routing behind the motherboard plate
  • Velcro straps included for easy cable management
  • Both side panels feature smart captive thumbscrews so no thumbscrews are lost
  • Colours available: Black
  • Case dimensions (WxHxD): 233 x 451 x 520mm
  • Case dimensions – with feet/screws/protrusions: 233 x 465 x 533mm
  • Net weight – window version: 8.5 kg
  • Package dimensions (WxHxD): 322 x 615 x 535mm
  • Package weight – window version: 10.2 kg

Our thanks to Fractal Design for providing the Define S for our review!

First Impressions

There isn’t much to say about the exterior if you’ve looked at the Define R5, though there are some differences to note. First the front panel on this Define S is solid; gone is the door that gave easy access to the screen filter and front fans – and of course 5.25” drives.

Removing the new front panel isn’t difficult as it simply snaps off, but the convenience of the hinged door is missed. There is a larger filter in place with the new design, however, and losing the optical bays also allows for a third fan mount for longer radiators.

A 140mm intake fan comes preinstalled

While we're looking at the front of the case we'll check out the front I/O for the Define S, which is very similar to the R5 but with USB 2.0 absent with this enclosure.

The side panels are different from those found on the Define R5, and though side panels are not the most glamorous aspect of a case though I do notice the loss of the latch mechanism from the R5's access panel. These panels simply slide on – a change that's understandable given this enclosure's lower price – and the back side panel is solid with a layer of insulation inside to lower noise.

As our review unit for the Define S is the windowed model the insulation is replaced on one side with a large clear plastic panel.

From the tripod reflection (totally intentional) you can see just how shiny the window is

Around back we see the standard ATX layout of the enclosure, and we have a larger than standard 140mm fan mount back here (also works with 120mm fans) populated by a quiet Fractal Design fan.

Accessible from the rear of the case is a screen filter for the PSU fan, and this simply slides out with minimal effort.

Before moving on I’ll quickly add that the packaging for the Define S is simple but effective, and the enclosure is well protected in the box for safe shipping like all Fractal cases I’ve received for review. In addition to an included instruction booklet the case hardware arrives in a small box that has every screw type separated into individual bags. Always appreciated!

Next we’ll take a look at the interior a go over a simple build with the Define S enclosure!

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