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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

  • Max graphics card length390 mm
  • Housing materialAL + SGCC + TG / Mesh
  • Supported motherboard sizesMicro ATX / Mini ITX
  • Dust filteringFront / Side
  • 3.5-inch internal bays1
  • 2.5-inch internal 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.

How it compares

Measured against everything we stock in Tower & Desktop PC Cases, at today’s prices. Recalculated every night.

Price $154.99
Pricier than about 72% of the 1,468 comparable items (median $100.99).
Max graphics card length 390 mm
Lower than about 57% of the 894 comparable items (median 400 mm).

New to this? Buying PC parts with Monero — what to check, what it costs to pay, and what is never asked for.

Specifications

Product
Brand nameCooler Master
Product lineMaster Frame Series
Model nameMF400M-KHNN-S00
Product colorBlack
Storage
3.5-inch internal bays1
2.5-inch internal bays1
Ports & slots
Front panel ports2 x USB 3.2 Gen 1 Type A / 1 x USB 3.2 Gen 2 × 2 Type C
1x 3.5MIc/ Audio Combo Jack
Size & build
Max graphics card length390 mm
Housing materialAL + SGCC + TG / Mesh
Dust filteringFront / Side
Fan mounting optionsFront: 2 x120 mm / 1 × 140 mm, 1 × 180 mm, 1 × 200 mm(Conditional Support)
Top: 3 x120 mm / 2 × 140 mm / 2 × 180 mm, 2 × 200 mm (Fan thickness = 25.5 mm)
Rear: 1x 120 mm
Bottom: 3x 120 mm, 2x 140 mm, 2x 180 mm, 2x 200 mm, and all fans up to 30 mm thick.
Product dimensions471 × 261 × 373.8 mm
Product weight8kg
Shipping weight10.66 kg
Package size584 × 470 × 368 mm
Compatibility
Supported motherboard sizesMicro ATX / Mini ITX
Radiator supportRear - Up to 120 mm / Top - Up to 240 mm / Top - Up to 280 mm / Top - Up to 360 mm
CPU cooler height limit190 mm
PSU length limit160 mm
More details
Included fansRear: 1x Sickle Flow 120 mm ARGB Black / 1x Sickle Flow 120 mm ARGB White

Other versions of this model

1 more in the same range

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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