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Fractal Design Define S Case Review

Fractal Design Define S Case Review. simple naming scheme of “S”. The Fractal Design Define S lends the appearance, sound dampening technology, and support for a wide variety of components from the widely popular Define Series, while introducing a new, innovative internal layout. The Define S case is packed with intelligently designed enthusiast-oriented features delivering a silent case with powerful and expansive air and liquid cooling support, presented in a stunning Scandinavian inspired construction.

The modernized internal layout of the Define S omits the optical drive bays, instead focusing on a clear straight airflow path and uncompromising water cooling support.
The Define S case reaches the highest level of silent computing through strategically placed dense sound-absorbing material, multiple ModuVent™ fan vent covers and finely tuned Dynamic Series fans

Key features


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  • Optimally designed for silent computing, while not compromising on airflow and cooling capabilities
  • Innovative internal layout, providing a perfectly straight airflow path to the CPU heatsink for air cooling set ups or extensive radiator mounting possibilities for water cooling set ups
  • Extensive water cooling support for a case of this size; housing radiators up to 420mm in the top and 360mm in the front
  • Including smart reservoir brackets; featuring drill-free reservoir mounting on the front of the motherboard tray and pre-drilled pump mounting holes on the bottom panel
  • Equipped with ModuVent™ fan slot covers providing the option of additional cooling or maximum sound absorption
  • Including two Fractal Design Dynamic GP14 140mm fans developed for superlative airflow while still maintaining low noise levels
  • Maintaining a dust-free interior with dust filters that cover the front and bottom air intakes
  • Introducing newly designed hard drive trays placed vertically behind the front partition of the motherboard tray; Three sturdy steel trays with vibration-dampening grommets allowing for installation of one 3.5″ or 2.5″ drive on each tray, without disrupting the airflow or interfering with the radiator mounting possibilities
  • An additional 2 dedicated steel SSD trays cleanly placed behind the motherboard tray
  • Long motherboard tray extending to the front panel contributing to an extremely clean build, hiding both hard drives and cables
  • Define S model is also available with a large window on the side panel


  • 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: 9.1 kg

Pricing on the day of review is £65-£75. with the side panel window version, being the more expensive.

[Packaging and bundle]

Exterior packaging for the Define S has not seen any major changes, compared other models in the lineup. The same style brown card box is what it ships in.  Today we have the black, windowed version. Like its predecessors other colour options are available, such as white

The included bundle, as you would imagine almost identical to the one we saw on the R5, Some new additions are present however such as the reservoir brackets. Which we will take a more in-depth look at soon.  Overall the kit is a very generous in terms of amount and the individual packing method is appreciated.

[Exterior Tour]

We start our tour of the Define S, at the case front and then we’ll work our way through the many features. If you’re not familiar with the Define R5, then do check out the review here first. As we will be referencing it often.
Ok then at first glance nothing seems to have changed between the R5 and Define S? Wrong, for starters the front door, isn’t a door panel anymore, instead it’s been tweaked in favour of a solid but removable panel. Why? You may ask… well the “Define S” does not have any optical drive bays, such there is nothing to hide behind a swing door any more.

With the panel removed, we find the original fan filter has been elongated to 360mm now, opposed to the 280mm one in the R5. Fractal use slits rather than fixed points for mounting the fans here, so there is a ton of flexibility for radiator or fan positions. We will explore this is more. A single 140mm fans is installed by default.

Moving up to the top section now and casting our eyes towards the roof. We have the I/O neatly forged into the top centre.  Consisting of a headphone and microphone jack, small reset button, large power button and 2x USB 3.0 ports. Notice they are not blue, If only all case manufacturers would make this change!

Along the top we find 3x ModuVent™ fan slot covers. Which are optional and configurable depending on how you set up the Define S. Leave them in place to contain the noise, or remove them to allow air  in/ out of the case.

Looking now at the underside, a removable filter covers the PSU area. Notice its longer than most we tend to see. The filter covers the center too, filtering any fans you add. Removal of the said filter is quick and efficient.

Finally we’ll examine the rear before taking a closer look inside.  There isn’t a great deal to mention here at all. A 140mm fan is visible at the top, with additional, mounts for a 120mm fan instead if you wished. Below it, 7x white removable PCI slot covers. Adjacent to them we would normally find a honeycomb ventilation area in most cases, instead Fractal have blanked off the area, in a quest to keep the “Define S” as quiet as possible.  At the base, a power supply mount.

[Internal Tour]

The side panel window here is simple rectangle shape, which is fitting for the design and intention of the product. The panel removes with smart captive thumbscrews, which means you won’t be losing them in a hurry, Something I find myself doing all too often! (fixed to the panel)The size of the window has been increased too.

Fractal Define S Review (37)
Now then, this is where things take an interesting turn for the better.  My first impression of the internals was simply “wow, that’s a lot of space!” really, there’s just so much room to work with here. A returning feature from the R5 is the motherboard tray that bevels near the centre (with two large grommets) and creates extra space on the right-hand side. This will prove vital on the Define S, as we’ll soon see.
I’ve mentioned it in past reviews and its key here too, rarely do I approve of the PSU area grommet I see in most cases. More often than not, I find them too small, or in the wrong location! Fractal have taken a no chances approach for such a problem here, with an oversized single grommet.
Fractal Define S Review (34)
As mentioned earlier, a large ventilation section is found in the floor for the PSU. In the centre we have a mounting option for 120mm/140mm fans. To the right of this, is a very welcome addition to the case, is a pump mount that should work with pretty much all DDC and D5 variants

Those horizontal slits on the right side of the motherboard tray are not a visual element, they are part of a key feature, when combined with the reservoir brackets

The strength of this feature, is the amount of control it grants you. No need to grab the drill here if you want to move your res! as the slits run from top to bottom (mostly) and you can adjust your reservoir location with ease. The actual plates, are fixed with screws on the rear side of the case.

With the res arms locked down, you can then either keep the extra drive bay plates out, or fill them up with drives as you desire. This smart addition to the case, which has replaced the removed hard drive cages on the other side , is only possible because of the bevelled motherboard tray that frees up space.

3 plates are supplied and will accommodate either mechanical  3x 3.5″ or SSD’s, including the two SSD trays below the CPU cut-out. The Define S can take a maximum of 5x 2.5″ drives.  Cabling is all kept in check with a 3 point Velcro system, and the logically placed grommets means cabling routing here is child’s plays.  The final strength of the Define S is the sheer amount of space between the motherboard tray and side panel. Peaking at 40mm for the most part.

[Watercooling Options]


Cooling system

  • Front: 3 – 120/140 mm fans (included is 1 Fractal Design Dynamic GP14 fan, 1000 RPM speed)
  • Rear: 1 – 120/140 mm fan (included is 1 Fractal Design Dynamic GP14 fan, 1000 RPM speed)
  • Top: 3 – 120/140 mm fan (not included) or 1 – 180 mm fan with 165mm hole spacing (not included)
  • Bottom: 1 – 120/140 mm fan (not included)
  • Side: 1 – 120/140 mm fan (not included)
  • Dust filters: Bottom and front intakes

Water cooling compatibility – Radiators

  • Front – 360, 280, 240, 140 and 120 mm radiators of all thicknesses
  • Top – 420, 360, 280, 240, 140 and 120 mm radiators. (A thickness limitation of 55mm for both radiator + fan applies on 420, 280 and 140 mm radiators)
  • Bottom – 120 mm radiator (Use of radiators in the bottom position limits the PSU length to 165 mm)
  • Rear – 120 or 140 mm radiator

Water cooling compatibility – Pumps

  • Pre-drilled holes on the bottom panel, supports many DDC and D5 variants

Water cooling compatibility – Reservoirs

  • Adjustable mounting brackets allow for almost any rectangular mounting screw pattern
  • Maximum distance between the mounting bracket screw positions: 350mm height / 80mm width

To say the Define S is flexible would be a massive understatement, let’s have glance at just some of the possible configurations

[360mm in the Front]

Fractal Define S Review (47)
With fans on both sides for a push-pull configurations, no limit in thickness unless you use a reservoir, even still a chunky rad should be fine!

[240mm in the floor?]

Fractal Define S Review (48)
Not strictly the intention of the floor mount, and only possible with a very small PSU, and modular cabling *not certain to work*

[360mm in the roof – Up to 420mm]

Fractal Define S Review (49)
No problem at all! You could technically fit one here another in  the front at the same time, but be mindful of your end tanks and output/input locations as they vary. A thickness limitation of 55mm (inc fans)

As the roof mounts are offset, compatibility for RAM and motherboards with tall heatsinks has been vastly improved, over the traditional centre mounts on most cases.

[Alternative use of reservoir mounts]

Depending on your res/pump combo you may not need the included mounts, as some have their own systems as shown above.

Rather than stick them back in the box you could use them elsewhere!


It’s time to wrap up and deliver our verdict on the Define S.  I must confess I seriously underestimated this case, when I glanced over the press release some months ago, quickly and wrongfully assuming it was just the R5 with the hard drive cages omitted. Which at the time made perfect sense to me, as I hardly use them…but then I looked at the price tag and just didn’t understand how it was so much cheaper than the R5. At the time the difference was about £35, today it’s closer to £25

Fractal have been very subtle and clever with the changes between the R5 and Define S. Let’s just go over the small changes that allow Fractal to sell the S for so much cheaper. Starting at the front of the case, the swing open door has been replaced with a flat fascia, because there is simply no need to have access anymore! (With no 5.25in drive bays behind it). The I/O has had a trim back and has only two USB 3.0  ports compared to the R5’s Dual USB 3.0 and 2.0, for me the sacrifice is just fine, as I rarely use them anyway.   The smart fan controller is also missing here on the S, perhaps a feature a few would have liked to see, but given the nature of the product (watercooling) it’s an understandable change.
The actual size of the case has been tweaked but you would hardly notice if you stood them side by side
Define S – 233 x 465 x 533mm (WxHxD)
R5 232 x 462 x 531mm (WxHxD)

With the S, standing a three millimetres taller, and depth increased by a  two millimetres. These tiny tweaks do make a difference though, with the then cabling routing space we saw on the back of the R5, now housing 3 hard drive bays, bringing to the total capacity to 3x 3.5″ or 5x 2.5″ (all hidden). A more notable change, to compliment the new reservoir mounting location is a larger window than  you would find on the R5. With the sole intention to show off your watercooling setup, don’t get me wrong you could go ahead and use the S with an air-cooled setup, but it would be a waste. A final change that isn’t likely to bother those who are eyeing up the S over the R5 is the side panel locking mechanism, now we have traditional line up and screw down panels, rather than the quick-release hinged side panel.

Missing features aside, the core of the case has all the strengths I found, when  I reviewed the R5 but the changes Fractal have implemented, do warrant it being a new model rather than and alternative version. Echoing what I said earlier about misunderstanding the product at first glance, it’s obvious a great deal of thought has gone into the new internal design here.  I’m not suggesting you should ignore the R5 either, there are small but key differences between these two products. The S is a ready to go out of the box product, and its focus is only watercooling alone. It’s common for a watercooler to purchase any case, strip away the hard drive cages, and optical bays, and drill in mounts for reservoirs/pumps. That’s all been taken care of, and  savings passed on to you,  with smart and meaningful changes to the product. It’s the approach I appreciate above all, really all fractal needed to do, was a sell a bay less R5 at lower cost, but they’ve gone further with a bigger window and clever motherboard tray design, yet still placed the S on the market for a fair bit less! Credit where it’s due!

To sum up, if it’s the exterior of the Define R5 or S that has drawn your attention, and I can why they would! You just need to ask, what’s the intention of your build? If you want mass amount of storage and small but welcome extras then go for the R5. Watercooling? It’s a no brainer then, the S is the one for you! With colour choices and optional side panel window the Define S a is worthy addition to ever-growing brilliant Define range.

Based on everything I’ve seen with the Define S is not only worthy of “Gold”, but because of the fantastic use of space with the design, I must compliment it further with our “Design award” Finally With a near insane low price tag, that I can’t ignore, it must be given the “Value” award too!


Fractal Design Define S Case Review. simple naming scheme of "S". The Fractal Design Define S lends the appearance, sound dampening technology, and support for a wide variety of components from the widely popular Define Series, while introducing a new, innovative internal layout. The Define S case is packed with intelligently designed enthusiast-oriented features delivering a silent case with powerful and expansive air and liquid cooling support, presented in a stunning Scandinavian inspired construction. The modernized internal layout of the Define S omits the optical drive bays, instead focusing on a clear straight airflow path and uncompromising water cooling support.…

Fractal Design Define S Case Review

Price - 9.9
Design - 9.9
Quality - 9.9
User Rating: Be the first one !
We would like to thank Fractal Design for providing the sample, we look forward to seeing more from them, in the near future

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