SilverStone RM21-304 2U Rackmount Server Chassis

SilverStone RM21-304 is a minimalist 2U rackmount chassis for lean NAS and edge servers. Supports Micro-ATX and Mini-ITX boards with 4 x hot-swap drive bays (3.5" or 2.5") and single Mini-SAS SFF-8087 backplane. Compact 480mm depth and lightweight at 6.3 kg.

Who it suits

• For cost-conscious edge deployments needing minimal footprint, 4 hot-swap bays support mixed 3.5" and 2.5" drives in a compact 480mm-deep 2U rackmount chassis.
• Small business NAS builders can use Micro-ATX or Mini-ITX motherboards, a single Mini-SAS backplane and four low-profile PCI/PCIe slots in a chassis weighing 6.3kg.
• Space-constrained operators get 480mm depth ideal for remote sites, branch offices, or dense rack arrangements where every millimeter counts.
• Less suitable for ATX motherboards, high-expansion builds or systems requiring eight or more hot-swap bays. Consider a compatible RM22 chassis for ATX builds, or RM21-308 for eight-bay Micro-ATX/Mini-ITX storage.

Before you buy

• The chassis supports Micro-ATX and Mini-ITX motherboards only. ATX and E-ATX boards are not supported; check the dimensions of any server motherboard before purchasing.
• The power supply is sold separately. The chassis supports compatible 2U single, 2U redundant or standard ATX PS2 power supplies up to 220mm deep and 86.3mm high.
• The single Mini-SAS SFF-8087 backplane connector serves four drive bays. Use a compatible SAS/SATA controller or correctly directed SATA breakout cable. SAS drives require a compatible SAS controller.

Model
SST-RM21-304

Chassis Form Factor
2U rackmount, compact depth

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

Main Metal Thickness
1.0 mm

HDD Backplane
4 ports SAS/SATA to Mini-SAS SFF-8087 x 1

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

Drive Support - Internal
1 x 3.5", 1 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 maximum height

Expansion Slots
4 x low-profile PCI / PCIe

Power Supply
2U single / 2U redundant / ATX PSU (not included)

PSU Dimensions
Up to 220mm deep, 86.3mm height

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
6.3 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 RM21-304 and RM21-308?

RM21-304 has 4 drive bays with a single Mini-SAS backplane connector, while RM21-308 has 8 bays with dual connectors. Both are 480mm deep and support Micro-ATX/Mini-ITX only. Choose RM21-304 for minimal deployments, RM21-308 for larger NAS.

Can I use SSDs in the RM21-304?

Yes. All 4 hot-swap bays accept both 3.5" HDDs and 2.5" SSDs. You can also add 1 x 3.5" and 1 x 2.5" internally for a total of 6 drives if needed.

What type of RAID controller does RM21-304 use?

The RM21-304 uses one Mini-SAS SFF-8087 connector for its four hot-swap bays. You can connect it to a compatible SAS/SATA HBA or RAID controller using an appropriate cable. For SATA drives, motherboard SATA ports may also be used with a suitable SFF-8087-to-4× SATA forward breakout cable. SAS drives require a compatible SAS controller. Check cable direction and controller compatibility before purchasing.