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Black open-frame mATX case with aluminium structure, mesh panels and one ARGB fan visible at the rear

Cooler Master

Cooler Master MF400M-KHNN-S00 MasterFrame 400 mATX PC Case

SKU CH-6BBQ-NJC6R MPN MF400M-KHNN-S00

Open-frame mATX chassis with aluminium frame, pre-installed 120 mm ARGB fan, top 360 mm radiator support and 390 mm GPU clearance

  • ColorBlack
  • Case MaterialAL + SGCC + TG / Mesh
  • Motherboard CompatibilityMicro ATX / Mini ITX
  • Dust FiltersFront / Side
  • Internal 3.5" Drive Bays1
  • Internal 2.5" Drive Bays1

Color Black

  • Modular frame supports vertical, horizontal or inverted layouts for desk flexibility
  • Open aluminium frame with mesh panels gives structural rigidity and unrestricted airflow
  • Fits Micro-ATX and Mini-ITX boards with room for nine fans and a 360 mm top radiator
  • 390 mm GPU clearance plus anti-sag bracket keeps heavy cards level
  • Front I/O includes two USB 3.2 Gen 1 Type-A and one USB 3.2 Gen 2×2 Type-C ports

MasterFrame 400 Modular mATX Chassis

The Cooler Master MasterFrame 400 is an open-frame aluminium chassis designed for Micro-ATX and Mini-ITX motherboards. Its modular structure allows vertical, horizontal or inverted orientation to suit different desk layouts. A single 120 mm ARGB fan is pre-installed at the rear for immediate airflow and lighting.

Builders Who Want Maximum Configuration Freedom

This case suits enthusiasts who want to design a custom cooling loop or high-airflow array using up to nine fan mounts and a top-mounted 360 mm radiator. The 390 mm GPU clearance and 190 mm CPU cooler height accommodate powerful components. Buyers needing more than one 3.5-inch drive bay or a fully enclosed panel design for silent operation should consider other form factors.

160 mm Power Supply Length Limit

The chassis accepts power supplies up to 160 mm long, a dimension that excludes many higher-wattage ATX units with deeper housings. Verify your PSU length before purchase to ensure it fits within the allocated space.

Highlights

  • Modular frame supports vertical, horizontal or inverted layouts for desk flexibility
  • Open aluminium frame with mesh panels gives structural rigidity and unrestricted airflow
  • Fits Micro-ATX and Mini-ITX boards with room for nine fans and a 360 mm top radiator
  • 390 mm GPU clearance plus anti-sag bracket keeps heavy cards level
  • Front I/O includes two USB 3.2 Gen 1 Type-A and one USB 3.2 Gen 2×2 Type-C ports

Specifications

BrandCooler Master
SeriesMaster Frame Series
ModelMF400M-KHNN-S00
ColorBlack
Case MaterialAL + SGCC + TG / Mesh
Motherboard CompatibilityMicro ATX / Mini ITX
Dust FiltersFront / Side
Internal 3.5" Drive Bays1
Internal 2.5" Drive Bays1
Front Ports2 x USB 3.2 Gen 1 Type A / 1 x USB 3.2 Gen 2 x 2 Type C
1x 3.5MIc/ Audio Combo Jack
Fan OptionsFront: 2 x120mm / 1 x 140mm, 1 x 180mm, 1 x 200mm(Conditional Support)
Top: 3 x120mm / 2 x 140mm / 2 x 180mm, 2 x 200mm (Fan thickness = 25.5mm)
Rear: 1x 120 mm
Bottom: 3x 120mm, 2x 140mm, 2x 180mm, 2x 200mm, and all fans up to 30mm thick.
Pre-installed FansRear: 1x Sickle Flow 120 mm ARGB Black / 1x Sickle Flow 120 mm ARGB White
Radiator OptionsRear - Up to 120mm / Top - Up to 240mm / Top - Up to 280mm / Top - Up to 360mm
Max GPU Length390 mm
Max CPU Cooler Height190 mm
Max PSU Length160 mm
Dimensions471 x 261 x 373.8 mm
Weight8kg
Shipping weight10.66 kg
Package size584 × 470 × 368 mm

Other versions of this model

1 more in the same range

Same family, different memory, cooler or clock — compare before you commit.

Questions about this item

Micro-ATX or Mini-ITX — which board fits best in this open frame?

Both form factors are supported; Micro-ATX uses the full width while Mini-ITX leaves extra room for cable routing behind the motherboard tray.

What does the 390 mm GPU limit mean for a triple-slot card?

A 390 mm card fits with the anti-sag bracket installed; measure your card including the power connector to confirm clearance.

The front panel has USB 3.2 Gen 2×2 Type-C — what speed does that actually deliver?

The port runs at up to 20 Gbit/s, so large file transfers to a compatible drive will hit the drive’s own sequential limit rather than the port’s.

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