1. Introdución
This manual provides detailed instructions for the assembly, operation, and maintenance of your Montech AIR 903 Base Midi-Tower computer case. Designed for optimal airflow and compatibility with a wide range of components, this case offers a robust foundation for your PC build.

Figure 1: Montech AIR 903 Base Midi-Tower
2. Configuración
2.1 Dimensions and Compatibility
The Montech AIR 903 Base Midi-Tower measures approximately 18.82 x 9.05 x 19.41 inches (465mm x 232mm x 492mm). It supports Mini-ITX, ATX, and Extended ATX (E-ATX) motherboards. Please note that using E-ATX motherboards may cover some rubberized cable holes.

Figura 2: Dimensións da caixa
2.2 Instalación de compoñentes
O caso ofrece ample space for various components:
- Liquidación da GPU: Supports graphics cards up to 400mm in length, accommodating high-end models like the RTX 4090.
- Altura do enfriador da CPU: Admite refrigeradores de CPU de ata 180 mm de altura.
- Compartimento PSU: A dedicated compartment at the rear supports power supplies up to 220mm in length without interfering with cables. This compartment can be extended by removing the hard drive cage.
- Baías de condución: The case includes one 3.5-inch drive bay (inside the removable cage) and five 2.5-inch drive spots (two behind the motherboard, two next to it, and one on top of the 3.5-inch cage). Note that the 2.5-inch spots are shared.

Figura 3: Disposición interna
2.3 Xestión de cables
The Montech AIR 903 Base features well-planned cable routing options, including rubberized cable holes and pre-attached Montech straps behind the motherboard tray. This allows for a clean and organized build, improving airflow and aesthetics.
2.4 Panel de E / S
The top I/O panel provides convenient access to essential ports and controls:
- 2 x portos USB 3.0 tipo A
- 1 x porto USB tipo C
- Audio In/Out jacks
- Botón de acendido
- Botón de reinicio
- LED button (for ARGB control)

Figura 4: Panel de E/S superior
3. En funcionamento
3.1 Fluxo de aire e refrixeración
The AIR 903 Base is designed for excellent airflow, featuring an innovative mesh front panel with a high ventilation rate. This design ensures optimal cooling performance for your components.

Figure 5: Mesh Front Panel
The case comes pre-installed with 140mm PWM fans (quantity may vary by specific model, Base typically includes 3). It supports additional fans and radiators:
- Fronte: Up to 3 x 140mm or 3 x 120mm fans. Radiator support up to 360mm or 280mm.
- Arriba: Up to 2 x 140mm or 3 x 120mm fans. Radiator support up to 360mm or 280mm.
- Traseira: 1 x 120mm or 1 x 140mm fan.
- Abaixo: 2 x 120mm fans (requires removing the hard drive cage).

Figure 6: Top Panel Mesh
3.2 Control de iluminación ARGB
If your case model includes ARGB fans, they are connected to a pre-installed ARGB controller and fan hub located behind the motherboard tray. The LED button on the top I/O panel allows you to cycle through various lighting modes. For advanced control, connect the 3-pin ARGB and PWM cables from the hub to your motherboard (if supported) to manage lighting and fan speeds via software.
4. Mantemento
4.1 Limpeza dos filtros de po
The front mesh panel can be easily removed by pulling it from the bottom, providing convenient access for cleaning the front fans and mesh. The top panel also features a magnetic dust filter for easy removal and cleaning. Regularly clean these filters to maintain optimal airflow and prevent dust buildup inside your system.
5 Solución de problemas
5.1 Fans or ARGB Not Functioning
Ensure all fan and ARGB cables are securely connected to the pre-installed hub and that the hub itself is connected to SATA power and the appropriate headers on your motherboard (if using software control). Check your motherboard's BIOS/UEFI settings for fan control options.
5.2 Front Panel Not Sitting Flush
Inspect the front mesh panel for any physical damage or dents that might prevent it from sitting flush. Ensure all clips are intact and properly aligned when reattaching the panel.
5.3 Component Fit Issues
Refer to the specifications section for maximum component dimensions. If installing a large PSU, consider removing the hard drive cage to provide more clearance. For large CPU coolers, ensure RAM clearance is sufficient; some coolers allow for fan elevation to clear tall RAM modules.
6. Especificacións
| Característica | Especificación |
|---|---|
| Marca | Montech |
| Nome do modelo | AIR 903 BASE |
| Número de modelo do artigo | AIR903BASEB |
| Tipo de caso | Torre media |
| Compatibilidade da placa base | ATX estendido, ATX, Micro-ATX, Mini-ITX |
| Dimensións do artigo (LxWxH) | 18.82 x 9.05 x 19.41 polgadas |
| Peso do elemento | 19.62 libras |
| Cor | Negro |
| Material | Vidro Templado |
| Número de portos USB 3.0 | 2 |
| Número de portos USB 2.0 | 2 |
| Método de arrefriamento | Aire, Auga |
| Tamaño do ventilador | 140 milímetros |
| Tipo de montaxe da fonte de alimentación | Montaxe traseira |
7. Garantía e soporte
For warranty information and technical support, please visit the official Montech websitio web ou póñase en contacto co seu distribuidor local. Garde o comprobante de compra para reclamacións de garantía.
8. Información importante de seguridade
Always disconnect power before installing or servicing components. Handle tempered glass panels with care to prevent breakage. Avoid exposing the case to extreme temperatures or humidity. Keep out of reach of children.