Review Index:

Fractal Design Define S Mid-Tower Enclosure Review

Manufacturer: Fractal Design

Introduction and First Impressions

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.

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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.

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Continue reading our review of the Fractal Design Define S enclosure!!

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

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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.

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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.

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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.

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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.

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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.

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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.

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

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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!

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

Video News

May 13, 2015 | 01:19 PM - Posted by BennyKsbandwidth (not verified)

Such a great review as always!

May 13, 2015 | 03:15 PM - Posted by Sebastian Peak

You're too kind :)

May 13, 2015 | 01:41 PM - Posted by jtiger102

Awesome review! I've been waiting for a review that goes through the temp and noise aspects.

I know I'm still in the minority, but I still use an optical drive to rip discs and play Blurays. I'll just get an external housing for my drive and use this case. :)

One correction for the review... In the Test Platform table, you list the Graphics card as a 750Ti OEM version. Should be the Lightning card as used in the review.

May 13, 2015 | 03:14 PM - Posted by Sebastian Peak

Thanks! And I corrected the table - definitely not the 750 Ti (that was meant for the recent Corsair cooler review).

May 13, 2015 | 02:12 PM - Posted by aintlds

Nice review. I would have like to have seen you really build the case out: full-size ATX mobo, all three 3.5" inch drive mounts and at lease one SSD mount installed and cabled, and another AIO for GPU cooling. Otherwise, I'm really glad you reviewed this case - I've been interested in it for some time.

May 13, 2015 | 03:19 PM - Posted by Sebastian Peak

Thanks, and I agree that more can be done with the Define S. I would also like to try out a full custom loop liquid cooling setup if we revisit it.

May 13, 2015 | 02:21 PM - Posted by Bryce (not verified)

Where can you buy them at?

May 13, 2015 | 07:41 PM - Posted by TheAmazingXemo (not verified)

Bought mine at Newegg: (Non-Window)

May 13, 2015 | 07:43 PM - Posted by TheAmazingXemo (not verified)

Here's the Windowed version:

May 14, 2015 | 01:40 AM - Posted by Lystfiskern (not verified)

Fractal Design puts out a great "clear canvas" to fit a nice looking watercooled build in :-) You seriously need to get your hands on some wc parts to feature in cases such as this one Sebastian!

Now if Fractal only where to update the 2010 Define Mini the m-atx guys also could have a viable option..... Its long over due! (u hear that @FractalJosh)

Great review.

May 15, 2015 | 01:29 PM - Posted by Sebastian Peak

Thanks - and I totally agree that enclosures like this scream watercooling. The build looked incomplete without it.

May 14, 2015 | 10:00 AM - Posted by LazarusIV

Great review, you'll have to throw some custom cooling stuff in there and check out the tolerances. I'd like to see someone squeeze a thin 420mm rad in top with a front rad or try to fit a couple 360mm rads in there. Keep up the great work!

Just bought my Define S to house my custom loop! Can't wait to get it!

May 15, 2015 | 01:30 PM - Posted by Sebastian Peak

Sweet - you'll have to hit us up with photos when the build is finished

May 15, 2015 | 05:56 AM - Posted by PortentousLad (not verified)

Great review!

So let me get this strait it's available in the US already, but over here in Germany I'm screwed?

I'm seriously considering having it shipped, couldn't possibly take longer.

Sorry for my whining I'm hoping for Fractal to notice.

May 15, 2015 | 09:57 PM - Posted by Problem

Very informative review. This is not a case for me since I still need 5 1/4" optical drives and front panel USB and audio jacks would be nice too. Thanks to your review this is one case I won't have to look at a second time.

May 18, 2015 | 09:17 PM - Posted by Brett from Australia (not verified)

Hi Sebastian Comprehensive and excellent review. I have a lot of time for the Fractal Define cases they offer excellent design and flexibility. The Define S looks a winner lots of good stuff in there.

June 16, 2015 | 09:54 PM - Posted by davidoff

Thanks for informative review. The case got very nice design. I like Fractal Design Define S with Window Side Panel from NewEgg

June 22, 2015 | 09:07 AM - Posted by The_Assimilator (not verified)

Now if only they made the Define R5 with this hard drive mounting mechanism.

July 31, 2015 | 02:48 AM - Posted by dDrac (not verified)

Awesome review and great review quality as always guys!

Keep up the lovely work!

On the mod side of things, how possible would it be to fit an SSI-CEB form factor in this? Does it have the less than 3cm space to not hit the psu? Or it needs further tampering?

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