■ Backplane support for 4 port SAS / SATA drives and 12 Gb/s Mini-SAS SFF-8087***

■ Supports four 2.5" / 3.5" SAS/SATA HDD / SSD

■ Includes three 80 x 15mm PWM fans

■ Independent drive status LED

■ Supports Micro ATX motherboards

■ Supports four low profile PCI / PCIe slots

■ Auto lock handle design easily secures to rackmount cabinet without screws


Test environment

RM21-304 backplane
Toshiba PX02SMF040 SAS 12G SSD
CPS06 – Mini-SAS HD(SFF8643) to Mini-SAS(SFF8087) cable



Model No. SST-RM21-304
Chassis form factor 2U
Motherboard Micro ATX (9.6" x 9.6"), Mini-ITX (6.7” x 6.7”)
Drive Bay External 3.5" or 2.5" HDD/SSD hot-swap x 4
Internal 3.5" x 1, 2.5" x 1 (up to 15mm), slim optical x 1 (up to 12.7mm)
Cooling System 80 x 15mm ball bearing fan x 3, 4000±10%RPM
Power Supply 2U single or 2U redundant / PS2 (ATX) up to 160mm deep and 86.3mm height (not included)
Limitation of CPU cooler 68mm
Power connector on HDD backplane 4-Pin peripheral x 2
Expansion Slot Low profile PCI / PCIe x 4
Front I/O Port USB 2.0 x 1, USB 3.1 Gen 1 Type-A x 1**
Front buttons Power On / Off, system reset
Indicators Chassis :
     Power LED x 1: Blue
     HDD Access x 1: Green
     LAN LED x 2: Green
HDD Tray :
     HDD Power LED x 8: Yellow
     HDD Access x 8: Blinking green
HDD backplane 4 ports SAS / SATA to Mini-SAS SFF-8087 x 1
HDD Interface SAS-1 / SAS-2 / SAS-3
SATA-1 / SATA-2 / SATA-3
Main metal thickness 1mm
Net Weight 6.3 kg
Dimension 430mm (W) x 88.5mm (H) x 480mm (D) 18.3 Liters
16.93" (W) x 3.48" (H) x 18.9" (D) 18.3 Liters
  **RM21’s USB internal cable is 800mm long, so if you are connecting an external enclosure to the USB 3.1 port, we recommend using it with shorter cables to prevent performance loss.
***Mini-SAS HD (SFF8643) to Mini-SAS (SFF8087) cable and 12 Gb/s SAS HD card required for 12 Gb/s performance. (e.g. SilverStone CPS06 & ECS05)


  • Q&A

Describe Ver Size Download
RM21-304 manual V1.0 3,388 KB
RM21-304 High resolution photos 14,978 KB
RM21-304 eDM (rm21-304-edm-en.jpg)   392 KB

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Single PSU List
Enhance ENH2150 500WEnhance ENH2160 600WEnhance ENH2170 700WEnhance ENH2180 800W 

Redundant PSU support list
Silverstone 2U Redundant PSU with dimension 231(L) x 82(W) x 84(H)mm
Kintron 2U Redundant PSU
Kintron RB2-G400VP 400WKintron RB2-G460VP 460WKintron RB2-G500VP 500WKintron RB2-G500VP 550W 
Zippy 2U Redundant PSU
Zippy M1D2-5300V0V 300WZippy M1D2-5400V0V 400WZippy M1D2-5500G0V 500WZippy M1W2-5600G0V 600WZippy DM1L2-5600V3V 600W
Zippy DM1L2-5650V3V 650WZippy DG1W2-5660V3V 660WZippy G1W2-5660V3V 660WZippy M1W2-5700K0V 700WZippy M1W2-5700G0V 700W
Zippy DM1L2-5700V3V 700WZippy DG1W2-5760V3V 760WZippy G1W2-5760V3V 760WZippy M1D2-5800V0V 800WZippy M1W2-5810V3V 810W
Zippy G1W2-5860V2V 860WZippy G1W2-5860V3V 860WZippy M1W2-5910V3V 910WZippy DG1W2-5960V3V 960WZippy G1W2-5960V3V 960W
Zippy G1W2-5960V2V 960WZippy T1W2-5A10V2V 1010WZippy G1W2-5A10V2V 1010WZippy DG1W2-5A10V3V 1010WZippy G1W2-5A10V3V 1010W
Zippy M1W2-5A10V3V 1010WZippy G1W2-5C00V2V 1200WZippy G1W2-5C00V3V 1200WZippy M1W2-5E00V3V 1400WZippy G1W2-5AE0G2V 1500W

No such information.