Define S

The Fractal Design Define S borrows its appearance, sound dampening technology, and support for a wide variety of components from the widely popular Define Series, while featuring a streamlined internal layout

  • Designed for silent computing and great airflow/cooling capabilities
  • Innovative internal layout with straight airflow paths
  • Extensive water cooling support for its size


View specifications


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.

The modernized internal layout 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 Dynamic Series fans.

Extensive cooling support

Optimally designed for silent computing without compromising on airflow and cooling capabilities
  • Innovative internal layout, providing a straight airflow path to the CPU heat sink for air cooling set ups or extensive radiator mounting possibilities for water cooling setups

  • Extensive water cooling support for a case of this size; housing radiators up to 420 mm in the top and 360 mm 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

  • Including two Fractal Design Dynamic GP14 140mm fans developed for superlative airflow while still maintaining low noise levels

  • Equipped with ModuVent™ fan slot covers providing the option of additional cooling or maximum sound absorption

Smart open layout and storage functionality

  • Maintaining a dust-free interior with dust filters that cover the front and bottom air intakes

  • 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

  • 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


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"Excellent are all the space and mounting options for anything liquid cooling related, a huge plus needs to be tagged for that alone. Overall the chassis is feature rich with the removable dust filters, offers enough HDD/SSD trays, and thus is aimed at the audiophile crowd."
"What's most impressive, however, is that the Define S is able to keep everything running cool while keeping noise levels to an absolute minimum.[...]Eschewing optical drive bays in favour of enhanced liquid-cooling support, the Define S targets a niche audience compared to the all-encompassing Define R5 and is able to do so at a keen price point."
"Fractal Design broke the mold of what we should expect from them, and in our humble opinion, for this sort of pricing, it is super tough to pass up on this design for something else more expensive, and may not offer all of the goodies that this does, even if it can compete with the water cooling options, the Define S is just that nice of a chassis."


  • 3.5" HDD/2.5" SSD positions
  • 2.5" dedicated SSD unit positions
    2 (fits SSDs up to 17 mm thick)
  • Expansion slots
  • Front ports
    2x USB 3.0, Audio in/out, Power button with LED (blue), HDD activity LED (blue), Reset button
  • Total fan mounts
  • Front fan
    3x 120/140 mm (included is 1 Fractal Design Dynamic GP-14 fan, 1,000 RPM speed)
  • Top fan
    3x 120/140 mm or 1x 180 mm with 165 mm hole spacing
  • Rear fan
    1x 120/140 mm (included is 1 Fractal Design Dynamic GP-14 fan, 1,000 RPM speed)
  • Bottom fan
    1x 120/140 mm
  • Side fan
    1x 120/140 mm
  • Dust filters
    Front fans, Bottom fans
  • Cable routing grommets
  • Fixed velcro straps
  • Captive thumbscrews
    Both side panels
  • Left side panel
    Industrial sound-dampened steel
  • Right side panel
    Industrial sound-dampened steel


  • Power supply type
  • Motherboard compatibility
    ATX, Micro ATX, Mini ITX
  • Front radiator
    360, 280, 240, 140 or 120 mm
  • Top radiator
    420, 360, 280, 240, 140 or 120 mm (a thickness limitation of 55 mm for both radiator + fan applies on 420, 280 and 140 mm radiators)
  • Rear radiator
    120/140 mm
  • Bottom radiator
    120 mm radiator (Use of radiators in the bottom position limits the PSU length to 165 mm)
  • PSU max length
    180/170 mm with a bottom 120/140 mm fan installed or 300 mm when not using any bottom fan
  • GPU max length
    425 mm with front fans installed, without compromising HDD capacity or 450 mm without front fans installed directly in line with the GPU
  • CPU cooler max height
    180 mm
  • Cable routing space
    20-40 mm


  • Case dimensions (WxHxD)
    233 x 451 x 520 mm
  • Case dimensions - with feet/screws/protrusions
    233 x 465 x 533 mm
  • Net weight
    9.1 kg
  • Package dimensions (WxHxD)
    322 x 615 x 535 mm
  • Package weight
    10.8 kg
  • Volume
    54.6 liters


  • Warranty
    2 Years
  • Package contents
    Define S computer case, User manual, Accessory box
  • EAN
  • UPC
  • Product code
  • Additional information
    Available for System Integrators