A Eurocard subrack is a modular card-cage enclosure for mounting plug-in circuit boards in a 19-inch equipment system. Its rails, front panels and optional backplane are based on standardized rack mechanics, but choosing the right frame depends on more than whether a board is called “Eurocard”: height, depth, slot width, connectors and the target bus all need to match.
What a Eurocard subrack does
A subrack holds printed-circuit boards vertically in guide rails, with front panels closing the slots. Depending on the system, it may also include or accept card holders, dividers, a backplane, connector hardware, rear panels, shielding and cooling provisions. The modular approach lets an integrator configure a frame around the boards and interfaces rather than use a fixed, one-piece enclosure. Verotec and Atos describe families with multiple heights, depths and accessory options (Verotec; Atos).
The mechanical framework is associated with IEC 60297-3 and DIN 41494. Those standards provide a common basis for rack and subrack dimensions; they do not, by themselves, guarantee that a particular board, connector or bus will work in a particular frame.
3U versus 6U: height and board outline
“U” denotes a nominal vertical increment of 44.45 mm in the Eurocard rack system. A Verotec dimensional guide gives that nominal increment and a 5.08 mm (1 HP) horizontal card-position pitch; usable panel and clearance dimensions are slightly smaller than nominal (Verotec Eurocard dimensional criteria).
#1 Best Overall
- Roomy Chassis: This 3U server case has 4 internal 3.5 inch HDD bays for ample storage capacity
- Expandable & ATX Compatible: 4 PCI expansion slots and ATX compatibility gives you options for expansion and customization
- Quiet Cooling: 2 pre-installed 80mm PWM front cooling fans provide excellent airflow and heat protection at reduced noise levels
- Front Panel Features: Front panel LED indicators for power, HDD, and LAN status monitoring allow quick, easy visual assessment of system operations
- Connectivity Options: Equipped with 2 USB 3.0 ports on the front panel for convenient high-speed data transfer and device connectivity
For a practical comparison, nVent’s 2021 CompactPCI manual lists typical board outlines of 100 × 160 mm for 3U and 160 × 233 mm for 6U. These are typical CompactPCI dimensions, not universal outlines for every board sold as a Eurocard; check the target board drawing and connector envelope before ordering (nVent CompactPCI Manual).
| Format | Nominal rack height | Typical CompactPCI board outline | Key fit check |
|---|---|---|---|
| 3U | One 44.45 mm U increment | 100 × 160 mm (nVent, 2021) | Confirm actual board height, depth and connector clearance. |
| 6U | Two 44.45 mm U increments | 160 × 233 mm (nVent, 2021) | Confirm actual board height, depth and connector clearance. |
Subracks are available in multiple depths, and the cited product families include differing options. Treat depth labels such as 160, 220, 233 or 280 mm as frame or board-depth classes to verify against the particular product drawing—not as interchangeable guarantees of usable PCB depth. Also check room for connectors, ejectors, wiring and any rear interface hardware.
Rank #2
- Includes 3×120mm fans (pre-installed) or supports 360mm liquid cooling radiators (pre-installed fans must be removed)."
- M/B size: ATX/MicroATX/Mini-ITX
- Drive Bays: 2*3.5 (internal)+1*2.5 (internal) Storage: suggest use of M.2/NVMe and PCIe based storage on M/B
- 8 slots PCI/PCIE expansion: Support max length=320mm with fans only / max length=305mm with AIO only
- PSU: SFX or SFX-L
Will it fit VME or CompactPCI?
VME and CompactPCI systems use Eurocard-style mechanical formats, but the shared mechanical concept is not enough to establish compatibility. The bus determines the connector and backplane arrangement; the front-panel hardware, keying, handles and any gasket or shielding requirements can differ as well. A CompactPCI manual, for example, specifies its own board and system details (nVent CompactPCI Manual).
Before selecting a frame, identify the bus and match the board to its bus-specific backplane and connector system. Check whether the subrack accepts the required backplane, connector mounts, front panels and rear-I/O or transition-module arrangement. A mechanically similar slot that cannot accept the right connector placement or interface is not a usable slot.
Rank #3
- max 8+4 x3.5 or 6+4 x3.5+2x2.5 drive bay
- ATX 12x9.6 / Micro-ATX 9.6x9.6 / Mini-ITX 6.7x6.7 (When using an ATX motherboard, part of it will be positioned under the PSU, limiting access to some components. The PSU will occupy two PCI slot spaces.)
- 2 x120mm + 1 x 80mm fan infront+2 x 60mm fan at rear pre-installed
- Material: Front Bezel+ handel Aluminum; Main Chassis- Zinc-Coated Steel
- 2 x front access USB 3.0 (compatible with USB2.0)
How to choose a subrack
- Measure the board and its interfaces. Record the PCB outline, connector envelope, required front-panel height and any clearance needed by handles or ejectors.
- Identify the electrical bus. Specify VME, CompactPCI or another interface and its connector and backplane requirements.
- Choose board height and depth. Select 3U, 6U or a purpose-designed mixed-height arrangement, then verify usable depth from the frame drawing.
- Calculate slot width. Card positions use a 5.08 mm (1 HP) pitch in the cited Verotec guide. Convert the available horizontal width into HP/TE positions, then allow for front panels, card edges and ejector clearance (Verotec Eurocard dimensional criteria).
- Set environmental and system needs. Decide whether the application calls for EMC shielding, conductive front panels, slot keying, rear transition modules, forced-air cooling or a shock-rated frame.
- Confirm what the order includes. Check whether guide rails, card retainers, front panels, dividers, backplane and connector hardware are included or must be specified separately. Also verify availability of replacement rails and panels.
When comparing candidate frames, assess board height and depth, usable width and HP pitch, backplane family, EMC and ESD provisions, airflow, shock and vibration ratings, rear-I/O needs, delivery as a kit or assembled unit, and replacement-part availability. A product description that says “3U Eurocard” alone does not resolve these fit and system questions.
Can 3U and 6U boards share a subrack?
Yes, mixed-height configurations are possible when the frame and system are designed for them. Atos lists 2 × 3U and mixed 2 × 3U/6U configurations, and VITA notes that 3U, 6U and 9U boards can be mounted in one subrack in a system designed for that arrangement (Atos; VITA). Do not assume an ordinary single-height frame will accept different board heights: check the rail layout, available openings, backplane geometry and connector alignment for the exact configuration.
Rank #4
- 3U server case has External Bay: 3x5.25" + Internal Bay: 8x3.5 max+1x3.5 to 2.5 adapter
- Cooling fan: 2x 80mm infront preinstalled + 2 x 60mm fan at rear (option)
- M/B size: Use ATX M/B support 2 x 5.25 / use Micro ATX M/B support 3 x 5.25
- Supports standard ATX PSU with top / bottom 120mm or side 80mm fan or SFX PSU (need to use the ATX to SFX braccket in screw box
- About GPU If remove a HDD cage max support 320mm to 340mm if donot remove the HDD cage, max support 240mm to 260mm please note 3U size is limited, please use the small power supply like SFX PSU to save space for cable management
When a rack case is a better choice
If an installation contains only a small number of boards, a full card cage may be unnecessary. Verotec’s 2013 brochure describes a 19-inch rack case that mounts standard Eurocards horizontally in a 1U or 2U envelope (Verotec). This is an alternative packaging format, not a substitute for checking the same board outline, connector access and cooling needs.
Quick Recap
Best Value
- 3U Rackmount Design: Professional 3U server chassis designed for standard 19-inch rack mounting, providing a robust and space-efficient solution for data centers and server rooms
- Extensive Drive Support: Accommodates 12 trayless 3.5-inch drive bays plus an additional fixed bay for 1x 3.5-inch or 2.5-inch drive, offering flexible storage expansion options
- Mini-ITX Compatibility: Supports mini-ITX motherboards with optimized internal layout for efficient component placement and cable management in NAS and server applications
- Cooling System: Features multiple pre-installed cooling fans with honeycomb ventilation pattern on front panel to ensure optimal airflow and thermal management for continuous operation
- Power Supply: Designed to accommodate SFX or SFX-L factor
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