SFF-8644 vs SFF-8654: Key Differences for Your Build

If you’re planning a high-performance storage or compute build, choosing the right interface matters—especially when it comes to high-speed internal and external cabling. Two of the most commonly used connector standards today are SFF-8644 and SFF-8654.

While both support high-speed data transfer and are widely used in enterprise hardware, each is designed for a specific use case. Here’s what you need to know to choose the right one for your setup.

SFF-8644: The External HD MiniSAS Standard

SFF-8644 is the standard used for external HD MiniSAS connections. You’ll typically find it on:

• External drive enclosures
• Host bus adapters (HBAs)
• Storage expansion shelves
• PCIe RAID cards with external ports

Key characteristics:

• Supports SAS 2.0, 3.0, with data rates up to 12Gb/s
• Compatible with MiniSAS HD cables
• Designed for external environments, with robust shielding
• Ideal for rack-to-rack and chassis-to-enclosure setups
• Has a larger footprint than SlimSAS connectors

SFF-8654: The Internal SlimSAS Standard

SFF-8654 defines the SlimSAS internal connector—a compact, high-density alternative to legacy MiniSAS. It’s used inside servers and storage systems to connect controllers, backplanes, and drives.

Key characteristics:

• Available in 4i (4-lane) and 8i (8-lane) configurations
• Supports PCIe Gen 4.0 (16GT/s per lane) and SAS 4.0 (24G)
• Enables high-density internal layouts
• Designed for internal routing in tight server chassis
• Offers a more compact footprint than SFF-8644

Which One Should You Use?

• Use SFF-8644 for external connections—such as linking a server to a storage expansion chassis or JBOD. It’s rugged, shielded, and designed for signal integrity over longer cable runs.
• Use SFF-8654 for internal PCIe or SAS connections—especially when space is limited and performance matters. It’s optimized for dense layouts and next-gen signaling standards.

We Carry Both—Engineered for Reliability

At Data Storage Cables, we stock a full line of SFF-8644 (HD MiniSAS external) and SFF-8654 (SlimSAS internal) assemblies—tested for signal integrity, shielding, and compatibility with today’s fastest protocols.