Universal 'Flex ATX' Military Enclosure

Flex ATX motherboards installed into a military certified enclosure to create a rugged deployable system.

For effortless technology insertion

Integrate directly without architecture transitions. Certified per MIL-461F & MIL-810G.

Retrofit and deploy your technology

Install customized or COTS hardware to build your system.

CM-ATX-FAC Description

The CM-ATX-FAC is a new generation of air-cooled, forced air enclosure that has been designed exclusively for applications where customers may wish to install commercial/industrial Flex ATX Motherboards for low cost, rapid deployment defense systems.

CM-ATX-FAC Power Supply and Motherboard area

Internal layout is divided into 2 independent metallic partitions. Motherboard area and PSU section at the side. This improves EMI/EMC performance & reduces PSU noise on system electronics.

The enclosure is available with or without power supply to provide extra space for the installation of electronic hardware that can be directly powered via the application platform. Alternatively, the enclosure may be retrofitted with any combination of electronics.

For stand-alone systems, a CM military PSU (adopted from our military ATR chassis line) delivers up to 850 watts of output power. The PSU will accept either AC or DC input voltages from 9-375VDC and 90-264VAC, supporting a wide variety of applications. An oversized capacitor bank on-board the PSU provides extended hold up time in the event of power failure.


Heat generated within the enclosure is dissipated via forced air convection. Dual rear exhaust fans draw ambient air through the enclosure carrying unwanted heat from the motherboard. Heat is also conducted through the chassis metalwork to the environment.

CM-ATX-FAC Cooling

Heat dissipation capacity is not dependent upon cold plate mounting but can improve thermal performance slightly and decrease payload Delta-T by approximately 5ºC, extending the MTBF of the enclosed electronics.

Units fitted with an integrated PSU may also benefit from an interdependently powered thermal protection system. A Temperature Supervisory Unit monitors enclosure temperatures, controlling rear fans and optionally installed cold start-up heaters. The TSU also provides remote control operation functionality.

Front panel indicators and front panel connectors are fitted according to customer requirements. Custom connectors may also be fitted where additional PCIe card capabilities are required.

Enclosure Performance




Payload Dissipation:350 Watts @ 55ºC (no cold plate)

The CM-ATX-FAC enclosure is expressly designed to simplify development, maintenance and logistics of military systems. The military Flex ATX enclosure yields substantial cost savings compared to native military open bus architectures typically found within the defense sectors, such as VPX, VME and cPCI, etc..

The enclosure can be easily mounted via base per-drilled threaded holes. Custom connector Front Panels, enclosure metalwork modifications and mounting options can be designed upon request, this may include for example, rear panel fixings, protruding bottom cover legs, self-clinching pilot pins, or other.

The small form factor enclosure is ideal for multiple military applications that are of limited space, weight sensitive, in close proximity to an operator and in a deploy & forget scenario.

Payload Electronics

The CM-ATX-FAC enclosure has been designed to accept ATX specification 2.2, Flex and Mini-ITX sized motherboards. Customers may integrate any variants of motherboard since universal mounting holes on the bottom cover have been machined. For electronics that are non ATX compliant, customization of mounting holes can be carried out upon request.

Paylaod Electronics

In spite that the CM-ATX-FAC enclosure has been designed for ATX motherboards, the enclosure can provide solutions for any custom or Modular Open Systems Architecture (MOSA) in order to deliver a military rugged solution.

The CM-ATX-FAC enclosure can support high power CPUs, FPGAs, PCIe cards, etc. The enclosure fits twin rugged DC fans that provide 120FCM of airflow. Military Rotron PX2 fans (130 to 200 CFM) maybe optionally fitted for high altitude applications.

PCIe card guides have been designed to provide expansion card stiffening. Card guides maybe optionally installed at fixing points on the inside front panel and lateral wall to provide ample strengthening.

System Management & Control

The CM-ATX-FAC can optionally fit a System Control Unit (SCU). This device interfaces the power supply and installed FlexATX motherboard. The SCU also incorporates a Temperature Supervisory Unit (TSU) that controls the Power Supply state, rear Fans and enclosure Heaters operation. The SCU is mandatory in triggering a pulsed power on signal for ATX motherboard booting.

Fully Customised Front Panel

Systems fitted with the TSU will benefit from the ability to intercommunicate with the PSU, interrogate and receive the following information:

  • Power Fail Monitoring.
  • Reset Control / Shut Down / Standby Control.
  • Thermal Monitoring.
  • LED indicator signaling.

The user defined Front panel is delivered full machined and silk screened, ready to accept customer connectors. I/O wiring and integration of payload electronics is our customers task. CM can provide this service on large order quantities upon request.

Case Study - Small Form Factor Rugged Defense Server

Rugged Defense Server, developed for military airborne applications for a leading ruggedized computing hardware solutions provider. The enclosure is fitted with a 16 core Intel® Xeon® processor and 128GB ECC RDIMM DDR4.

Small Form Factor Rugged Defense Server

The configuration boasts twin 10G SFP+ ports, 6 GbE LAN ports, IPMI, VGA, Serial and USB ports that are fully military compliant and qualified. This 'turn-key' system builds on Super Micro Computer, Inc motherboard technology.

Front Panel connectors and signals lines are delivered fully customized for the application.

Signal integrity, wiring density and performance are all highly optimized in this COTS SwaP solution. The CM-ATX-FAC enclosure is supplied with a full military grade PSU and all premium features of the CM's supervisory system.

CM-ATX-FAC Power Supplies

CM-ATX-FAC enclosure PSUs support a wide variety of AC/DC input voltages (MIL-STD-704 & MIL-STD-1275) and customer defined DC power output combinations up to 850 Watts.

The CM-ATX-FAC fits the C-850W model as standard for compliance with ATX specifications. Refer to 3U PSUs if your application does not use an ATX motherboard.


All PSU models are fitted with Power Fail Monitor, remote voltage sensing, output voltage trim-up, time-delayed protection fuses, rear fan fuse and DC/DC converter remote shutdown.

To comply with MIL-STD-461E, a high capacity integrated EMI/EMC input voltage filter is fitted as standard.

Single-phase AC PSUs are fitted with a VICOR military Filter and Autoranging Rectifier Module (FARM) to provided EMI filtering, autoranging line rectification and inrush current limiting to meet MIL-STD-461E category A1b specifications for Electromagnetic Compatibility.

ATX FAC Power Supply Unit

200VAC 3-Phase PSU versions additionally incorporate AC/DC rectifier stage prior to the VICOR FIAM front-end modules.

DC PSUs are equipped with a VICOR military Filter and Attenuator Module (FIAM). This front-end device is fitted prior to the DC/DC converters to provide EMI filtering, inrush current limiting and transient protection.

Front-end FIAM modules are protected against DC reverse polarity. An optional reverse polarity diode may be fitted in series with power connector input pin IN (+).

The CM-ATX-FAC PSU incorporates isolated DC/DC converters and oversized hold-up capacitors to ensure proper operation during short power line failures. Outputs are protected against short-circuit, thermal-shutdown etc. PSUs are custom made to match the enclosure mechanics.

CM ATX Power Supply Unit

The CM-ATX-FAC PSU is attached to the chassis side panel to provides both conduction & convection cooling, internal air also aids in dissipating heat generated.

Forced air drawn through the chassis is exhausted, dissipating the majority of heat generated. Heat is also dissipated via thermal conduction to the enclosure frame.

Read More

Supervisory System

A Temperature Supervisory Unit (TSU) is fitted as standard for ATX systems. This device protects electronics against extreme climatic conditions, switching the power supplies OFF (Standby) when the internal temperature is under or over the established limits. Users may set HI & LO temperature trip-points to regulate and optimize the system safety operational temperature range.

Temperature Supervisory Configuration
Switch-OFF Switch-OFF NORMAL OPERATION. Both PSU and TSU operate normally.
Switch-OFF Switch-ON PSU in STAND-BY MODE. The PSU converters are forced to stand-by. No DC power is available to the digital payload. The TSU operates normally.
Switch-ON Switch-OFF BATTLE MODE (TSU DISABLED). The PSU is operating normally. The TSU is not allowed to shut-down the system power regardless of temperature.
Switch-ON Switch-ON PSU in STAND-BY MODE. The PSU converters are forced to stand-by. No DC power is available to the digital payload. The TSU is disabled.

Heating elements are also fitted for mitigating against cold startups. An ‘early warning’ signal advises the digital electronics prior to shutdown-to-standby, allowing critical data to be orderly stored and saved. Power is restored once internal temperatures are within operational limits. All functions can be user enabled or disabled by soldered bridges.

TSU Power Supply Specifications
  • Provides +5VTSU DC output voltage, up to 2 Watts.
  • Autorange input 80-265 VAC 20-1000 Hz. 7 mA typical.
  • 28VDC 32mA, 48VDC 18mA, 270VDC 4mA typical (±40%).
  • Output current short circuit protection in +5V_TSU: 400 mA.
TSU Heater Elements
  • DC 12 VDC @ 3.3 Amps. - DC 270 VDC @ 0.15 Amps.
  • DC 28 VDC @ 1.5 Amps. - AC 115 VAC @ 0.3 Amps.
  • DC 48 VDC @ 0.8 Amps. - AC 220 VAC @ 0.18 Amps.

The user defined Front panel is delivered full machined and silk screened, ready to accept customer connectors. I/O wiring and integration of payload electronics is our customer's task. CM can provide this service on large order quantities upon request.

System Management & Control

Systems fitted with the CM integrated Power Supply will benefit by having the ability to intercommunicate with the PSU, interrogate and receive the following information: A System Control Unit (SCU) is fitted as standard for ATX systems for motherboard booting compliance.

  • Power Fail Monitoring.
  • Reset Control / Shut Down / Standby Control.
  • Thermal Monitoring.
  • LED indicator signaling.
CM ATX Enclosure System Control Unit

Thermal Monitoring - The Low and High TSU temperature trip points are user adjustable through two multi-turn trimming resistors located in the power supply PCB. Factory presets fitted with fixed resistors can be installed in production series.

Thermal Heaters - Resistive heating elements powered by the TSU are bolted to the enclosure frame in order raise internal temperatures during cold startups.

Battle Short Switch - Ability to disable the TSU during emergency or battle situations via a remote ‘Battle short’ switch. This bypasses/overrides all critical TSU functionalities despite the risk of payload temperature over-stress.

Reset Push Button - A remote push button allows to reset the Switch digital payload without switching off the mains breaker. TSU remote operations can be manually activated by an operator or via a master computer.

Delayed Shut-down - An AC/DC FAIL* signal advises the CPU when power failure is imminent prior to power shut-down. Ethernet communications and critical data in memory, etc may be orderly stopped or saved.

PSU Standby Switch - Allows the user to manually set the system to ‘low power’ Standby mode without requiring to switch off the mains breaker, should the system be required to operate for a few hours but remain available on demand.

Power Supply - TSU circuitry is powered by an independent +5VTSU @ 2 Watt PSU. This module is permanently connected to the power input & remains operational during Standby.

Front Panel LEDs - TSU status & operations can be visualized in real time via three chassis front panel LEDs: TSPW (TSU power on), TSHI (system over temperature) and TSLO (system under temperature).


Removable Covers with Captive Screws
Removable Covers
The machined enclosure covers/panels are easily removable for maintenance and disassembly via stainless steel captive screws.
Mounting Holes
Mounting Holes
The enclosure can be easily base plate mounted via eight per-drilled threaded holes. A mounting tray option is also avilable.
Cooling Fans
Cooling Fans
Fitted with twin rear cooling fins and EMI shielded finger guards on the rear cover. Opional Rotron high altitude military fans available.
Custom Front Panel
Front Panel
Custom layout with client logo, connectors & silk-screening or a general purpose panel with MIL-C-38999 connectors is supplied.
Front Panel Indicators
LED Front Panel Indicators
Up to 8 front panel LED indicators for chassis monitoring; power on/off status, system board failure, input voltage, temp., etc.
Marking Plates
Marking Plates
Front Panel marking plate area for system specification data and Bottom Cover marking area for serial number indication.
Sealed EMI Gaskets
Sealed EMI Gaskets
All joints incorporate particle-filled silicon rubber DTL-83528C EMI beading for superior shielding, environmental sealing & thermal transfer.
Cold Start-up Heater
Cold Start-up Heater
Resistive heating elements can be optionally installed and are controlled by the supervisory system to minimize the effects of cold startups.
Inline Input Filter
Inline Input Filter
A high capacity integrated EMI/EMC input voltage filter and PSU module discrete parts are fitted as standard to comply with MIL-STD-461F.
Hold-up Capacitors
Hold-up Capacitors
PSU incorporates oversized hold-up capacitors intended to maintain DC voltages to payload electronics in the event of momentary power loss.
PCIe Card Clamps
PCIe Card Clamps
Optional Universal PCIe card edge clmaps can be supplied to provide additonal support to PCIe cards in high vibration environments.
Military Paint and Coatings
Military Paint & Coating
Painted with a 3-layer military grade epoxy paint & primer. Machined aluminum anti-corrosion treatment MIL-STL-8170, Chromium(VI) Free.


  • Flowthrough Air Cooled Enclosure (open)
  • Maintenance free operation
  • Stand alone low weight ATR
  • Low weight, optimized footprint
  • Fully MIL-STD-461G certified
  • For Flex ATX form factor electronics
  • Removable Covers and Panels
  • In-line EMI/EMC MIL-STD-461F Filter
  • Integrated Temperature Supervisory Unit (TSU)ª
  • Front panel user indicators
  • Flexible I/O wiring
  • Low Profile Mounting Tray with quick release system ready
  • Military Operating Temperature (-40°C | +85°C)
  • Customizable to specific requirements


WIDTH 310 mm
HEIGHT 140 mm
DEPTH 286 mm
PAYLOAD AREA 222 mm x 232 mm x 120 mm
WEIGHT .... Kg
PSU V-INPUT 28 VDC ±30%, 48 VDC ±30%, 72 VDC ±30%, 270 VDC ±30%, Autorange 90-132 VAC RMS & 180-264 VAC RMS 47-880 Hz, 3-Phase 200 VAC ±30% 47-880 Hz
EXT. REAR FAN 2 Rugged or 2 Rotron PX2
STDF 120 CFM (Rugged)
F115-400 130 CFM (Rotron PX2)
F200-400 240 CFM (Rotron PX2)
FRONT PANEL AREA 55 mm x 200 mm
MTBF 25° GB 82,000 Hours, 65° AIC 27,000 Hours
OPERATING TEMP -40°C to +85°C Operating Temperature, -55°C to 100°C Storage Temperature
MOUNTING OPTION CM-ATX-TR (Baseplate mounting)


This highly optimized small form factor enclosures incorporate all proprietary technologies, features and well established mechanical & electrical solutions developed during the past 30 years.

MIL Certificates

  • MIL-STD-461G Radiated Emissions  Testing

    Radiated Emissions

  • MIL-STD-461G Con. Susceptibility  Testing

    Con. Susceptibility

  • MIL-STD-461G Radiated Emissions  Testing

    Radiated Emissions

  • MIL-STD-461G Con. Susceptibility  Testing

    Con. Susceptibility

Ordering Information

Generic Part Number:
Enclosure Cooling Technique
  • CM-ATX-FAC: Flowthrough Air Cooled (open).
/I Primary Input Power Voltage
  • 115VAC: 115 VAC Input @ 40-880Hz.
  • 220VAC: 220 VAC Input @ 40-880Hz.
  • 12VDC: 12 VDC Input (9-36 VDC @ 50W).
  • 28VDC: 28 VDC Input (9-36 VDC @ 50W or 18-36 VDC @ 75W).
  • 48VDC: 48 VDC Input (36-75 VDC @ 75W).
  • 270VDC: 270 VDC Input (180-375 VDC @ 75W).
/F Fan Assembly
  • STDF: 2x 60CFM DC Rugged Fans.
  • F115-400: 2x PX2 Rotron Military High Altitude Fans (65CFM each) fitted for 115VAC @ 400Hz.
/C Color
  • B: Black, G: Navy Grey, E: Army Dark Earth, W: White, R: Red, PT: Platinum, YW: Yellow, GN: Green, BLU: Dark Blue, CR: Chromate MIL-C-5541 or O: Other (user defined).
/MT Mounting Tray
  • CM-ATX-TR: Optional Mounting Tray.
Part Number Example:
  • CM ATX Form factor Enclosure.
  • Flowthrough Air Cooled Enclosure (Open, Non-Sealed).
  • 115VAC @ 400 Hz input power supply.
  • 850W Power Supply (fitted as standard).
  • User defined front panel layout (requires customer drawing).
  • Enclosure color is Black.