SilverStone RM400 4U Rackmount Server Chassis - Flexible Server Build

Our review of the SilverStone RM400 finds it is a practical, no-frills 4U rackmount chassis for professionals who need a roomy, secure case for server or workstation builds. The single biggest reason to buy is its support for large motherboard form factors up to SSI-CEB and accommodation for standard ATX or Mini redundant power supplies, which gives builders flexibility for dense, rack-oriented systems. The RM400 is clearly aimed at engineers and small data center teams who prioritize space, drive bay flexibility, and a simple front lock over aesthetic extras.

Key Features

• SSI-CEB and ATX support: Accepts large server-class motherboards and standard ATX boards so you can choose a high-performance platform.
• Three 5.25 in drive bays: Provides flexible installation for optical drives, hot-swap bays, or front-mounted controllers when serviceability matters.
• Redundant power supply compatibility: Fits ATX (PS2) or Mini redundant power supplies up to 160mm deep to support resilient power configurations.
• Front USB 3.1 Gen1 ports: Includes 5Gbps USB connectivity that is backward compatible with USB 2.0/1.1 for fast external transfer and tool-less setup convenience.
• Included cooling: Ships with one 120mm and one 80mm PWM fan to provide baseline airflow for server components out of the box.

Who It's For

The RM400 is best for IT professionals, lab technicians, and small data center operators who need a durable 4U chassis that supports larger server motherboards like SSI-CEB and offers flexible drive bay options. Its front door with key lock and room for redundant power supplies appeal to environments that require controlled access and uptime.

Those who should look elsewhere include users seeking silent consumer desktop cases, compact home lab builds that must fit into shallow racks, or buyers wanting built-in advanced cable management and aesthetic accents; the RM400 is functional rather than decorative.

Pros & Cons

Pros

• Roomy interior that accommodates large ATX and SSI-CEB motherboards and multiple PCIe slots for expandability.
• Three front 5.25 in bays give clear options for drives or front-panel devices when serviceability matters.
• Durable construction with a front door key lock improves physical security in shared rack environments.
• Front USB 3.1 Gen1 ports provide modern connectivity while remaining backward compatible.

Cons

• Some users report mixed installation experience with ATX motherboards, and noise levels vary depending on fan setup and components.

Specifications

Form factor support	SSI-CEB / ATX / mATX / mITX
Drive bays	3 x 5.25 in front bays
Power supply	ATX (PS2) / Mini redundant up to 160mm deep
Expansion slots	Standard profile PCI / PCIe x7 slots
Front I/O	USB 3.1 Gen1 (5Gbps), backward compatible with USB 2.0/1.1
Cooling included	One 120mm PWM fan and one 80mm PWM fan

Our Verdict

The SilverStone RM400 is a solid, value-oriented 4U rackmount chassis for professionals who need flexibility for large motherboards, multiple front 5.25 in devices, and redundant power options. It is good value for engineers and small data centers that prioritize expandability and security over visual design.

Frequently Asked Questions

Does it support redundant power supplies?
Yes. The RM400 supports ATX (PS2) and Mini redundant power supplies up to 160mm deep.

What motherboard sizes fit this chassis?
The case accepts SSI-CEB, ATX, mATX, and mITX motherboard form factors.

Are USB 3.1 ports available on the front?
Yes. Front I/O includes USB 3.1 Gen1 ports at 5Gbps that are backward compatible with USB 2.0 and 1.1.