SilverStone RM21-308 2U Rackmount Server Chassis

SilverStone RM21-308 is a compact 2U rackmount chassis for small NAS and edge server builds. Supports Micro-ATX and Mini-ITX boards with 8 x hot-swap drive bays (3.5" or 2.5") and dual Mini-SAS SFF-8087 backplane. Shallow 480mm depth saves rack space.

Who it suits

• For space-constrained racks, the RM21-308 fits in 2U with only 480mm depth, saving precious rack space compared to deeper 2U models.
• Small NAS and edge server builders get 8 hot-swap bays supporting mixed 3.5" HDD and 2.5" SSD drives in one compact chassis.
• Budget-conscious integrators appreciate the simplified design: Micro-ATX and Mini-ITX boards only, 4 PCIe slots, lightweight at 7.3 kg.
• Not for full-size ATX or E-ATX systems, gaming builds, or high-expansion server setups. This is designed for lean, compact edge deployments.

Before you buy

• The chassis supports Micro-ATX and Mini-ITX motherboards only. ATX, E-ATX and SSI-EEB boards are not supported. Consider a compatible RM22 chassis for larger motherboards.
• The power supply is sold separately. Compatible 2U single, 2U redundant or ATX PS2 power supplies are supported up to 220mm deep and 86.3mm high.
• The backplane uses two Mini-SAS SFF-8087 connectors, not Mini-SAS HD SFF-8643. Check HBA or RAID controller compatibility and cable direction before purchasing.

Model
SST-RM21-308

Chassis Form Factor
2U rackmount, compact depth

Motherboard Support
Micro-ATX (9.6" x 9.6"), Mini-ITX (6.7" x 6.7")

Main Metal Thickness
1mm

HDD Backplane
8 ports SAS/SATA to Mini-SAS SFF-8087 x 2

Drive Support - External
8 x 3.5" or 2.5" hot-swap HDD/SSD

Drive Support - Internal
2 x 2.5" (up to 15mm), 1 x slim optical (up to 12.7mm)

Interface
SAS-1 / SAS-2 / SAS-3, SATA-1 / SATA-2 / SATA-3

Power Connectors
4-pin peripheral x 2

CPU Cooler Clearance
68mm

Expansion Slots
4 x low-profile PCI / PCIe

Power Supply
2U single or 2U redundant / PS2 (ATX) up to 220mm deep and 86.3mm height (not included)

Front I/O
1 x USB 2.0, 1 x USB 3.1 Gen 1 Type-A

Front Panel Controls
Power On/Off, system reset

LED Indicators - Chassis
Power (blue), HDD Access (green), LAN x 2 (green)

LED Indicators - HDD Tray
HDD Power x 8 (yellow), HDD Access x 8 (blinking green)

Dimensions
430mm (W) x 88.5mm (H) x 480mm (D)

Volume
18.3 litres

Net Weight
7.3 kg

1 YEAR WARRANTY

Avertek Enterprises Pte Ltd
25 Kallang Ave #03-03, Singapore 339416
Contact: 6341 7839

How long will it take to receive my purchase?

Standard Shipping - 3 to 5 days
Express Shipping - 1 to 2 days

Can I opt for store pickup?

Yes, we are open daily for collection from 11 AM - 6.30 PM.
Address: 1 Ubi View #01-22, Focus One Building Singapore 408555 (Door located nearest to carpark exit gantry) We will contact you once your order is ready for collection!

What is the difference between RM21-308 and RM22-308?

The RM21-308 is a compact 480mm-deep 2U chassis supporting Micro-ATX and Mini-ITX motherboards, with eight hot-swap bays and four low-profile expansion slots. Check the RM22-308 specifications if you need support for larger motherboards or additional expansion cards.

Can I use 2.5" SSDs in the RM21-308?

Yes. All 8 hot-swap bays support both 3.5" HDDs and 2.5" SSDs. You can mix them in the same chassis for hybrid storage pools.

Does the RM21-308 use the same SAS connectors as other SilverStone models?

The RM21-308 backplane uses two Mini-SAS SFF-8087 connectors. Other SilverStone chassis may use different connector types, so check each model's specifications. For 12Gb/s SAS performance, SilverStone specifies a compatible 12Gb/s SAS host card and a Mini-SAS HD SFF-8643-to-SFF-8087 cable.