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Cooler Master MasterBox NR400 - mATX Mini Tower Case with Tempered Glass Side Panel, 2 x 120mm Pre-Installed Fans, Flexible Air Flow Configurations, Cable Management
Cooler Master

Cooler Master MasterBox NR400

Bottom line: The Cooler Master MasterBox NR400: Full mesh front and top panels, with a magnetic top dust filter and a fixed bottom filter; main trade-off: micro-ATX and mini-ITX boards only; full ATX motherboards will not fit.

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By , Founder & Editor-in-Chief · Listing data updated

Mike Perry — Hardware researcher since 2014, focused on GPU performance across gaming, rendering, and local-LLM inference. Synthesises community benchmarks, manufacturer specs, and public forum data into actionable buying guides.

Pros & Cons

Pros

  • ✓ Full mesh front and top panels, with a magnetic top dust filter and a fixed bottom filter
  • ✓ Two 120mm fans pre-installed, one front and one rear
  • ✓ Front fits a 280mm radiator; top fits a 240mm radiator or 2 x 120/140mm fans
  • ✓ Fits graphics cards up to 346mm long and CPU air coolers up to 166mm tall
  • ✓ 22mm of cable space behind the motherboard tray, plus rubber grommets for routing

Cons

  • ✗ Micro-ATX and mini-ITX boards only; full ATX motherboards will not fit
  • ✗ PSU capped at 140mm with a front radiator or HDD cage (325mm without)
  • ✗ Only two fans included; filling 3 front + 2 top slots means buying more
  • ✗ Bottom dust filter is fixed; only the top filter is magnetic for quick removal

Manufacturer description

The MasterBox NR400 combines versatile cooling and expandability with a minimalistic yet finely detailed design. With an outstanding array of cooling options, the front panel and top mesh panel facilitate excellent airflow performance. Internally, the builder-friendly layout compliments the compact design by maximizing the use of available space and incorporating clean aesthetic elements such as shrouding and cable management space. The MasterBox NR400 features a tempered glass side panel, fastened at the rear panel to keep the surface immaculately flush.

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SpecPicks Verdict

SpecPicks scored Cooler Master MasterBox NR400 using a rating × review-volume × price-fit model applied to published specs and reviews across the pc cases category. Cooler Master's pc cases lineup sits within the broader category mid-tier; price and specs are the deciding factors over brand loyalty here. Judge it on the specification table and the price rather than on sentiment: check the figures that decide your use case, then put it side-by-side with two or three close alternatives in the Compare tool before clicking through.

Common buyer scenarios for pc cases of this kind: matching it to an existing build, replacing a failing part, or upgrading from a previous-generation equivalent. Check the spec table below against your current setup — particularly socket / form-factor / power-rating fields — and confirm compatibility on the retailer's listing before purchase. Prices and stock are set by the retailer and may have moved since this page was last updated.

Key Features

  • MINIMALIST DESIGN, OPTIMIZED PERFORMANCE - The NR400 features full mesh front & top panels to optimise internal air flow and cooling performance - the top panel includes a magnetic dust filter (and a fixed filter in the bottom panel)
  • TEMPERED GLASS SIDE PANEL - System builds can be showcased through a flush tempered glass panel, which fastens discreetly via the back panel to ensure a smooth surface along the side of the chassis
  • EXCELLENT FAN AND RADIATOR SUPPORT - Two 120mm fans come preinstalled in the front and rear panels - the front panel can support either 3 x 120 or 2 x 140mm fans and a radiator up to 280mm, while top supports 2 x 120/140mm fans or a 240mm radiator
  • IMPRESSIVE CLEARANCES - Supports both micro-ATX and mini-ITX motherboards, CPU coolers up to 166mm in height, graphics cards up to 346mm in length, and and an ATX PS2 power supply up to 140mm in length (325mm without a front radiator or HDD cage)
  • SMART INTERNALS - Cabling can be neatly routed through rubber grommets, while 22mm of clearance space behind the motherboard provides ample room for cable management - the HDD cage can be repositioned for a longer PSU or additional radiator space

Full Specifications

BrandCooler Master
Colorblack
Fan Size12 centimeters
MaterialTempered Glass
Case TypeMini-Tower
Model NameNR400
Unit Count1 Count
Light ColorBlack
Model NumberMCB-NR400-KGNN-S00
Built-In MediaComputer Case
Cooling MethodAir
Item Type NameMini tower micro ATX, tempered side glass, 2 x 120 mm preinstalled fans, flexible airflow and wiring management, no optical disc burner
Number of Fans6
Mfr Part NumberMCB-NR400-KGNN-S00
Total Usb Ports2
Antenna LocationIndoor
Compatible DevicesPC
Enclosure MaterialTempered Glass
Total USB 2.0 Ports2
Total USB 3.0 Ports2
Full listing titleCooler Master MasterBox NR400 - mATX Mini Tower Case with Tempered Glass Side Panel, 2 x 120mm Pre-Installed Fans, Flexible Air Flow Configurations, Cable Management

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Cooler Master MasterBox NR400 - mATX Mini Tower Case with Tempered Glass Side Panel, 2 x 120mm Pre-Installed Fans, Flexible Air Flow Configurations, Cable Management is listed on Amazon. Price, availability, shipping and returns are set by Amazon and its sellers — check the listing for current terms. SpecPicks earns a small commission on qualifying purchases — thank you for supporting independent review work.

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Cooler Master MasterBox NR400 - mATX Mini Tower Case with Tempered Glass Side Panel, 2 x 120mm Pre-Installed Fans, Flexible Air Flow Configurations, Cable Management
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