Solid state drives (SSDs) have become increasingly popular in personal computers and data centers thanks to their faster data access speeds and improved reliability compared to traditional hard disk drives (HDDs). When selecting an SSD, one of the key factors to consider is the interface that will connect the SSD to the rest of the computer system. The interface impacts the maximum throughput of the drive and compatibility with various motherboards and systems. This article will provide an overview of the most common SSD interface options available today and discuss the advantages and disadvantages of each to help readers select the right interface for their needs.
SATA (Serial ATA) is the oldest and most common SSD interface in use today. SATA has gone through several revisions with the latest SATA III providing a maximum throughput of 600MB/s. SATA SSDs use the standard SATA data and power connectors making them natively compatible with most consumer PC motherboards and laptops. Here are some of the key advantages and disadvantages of SATA SSDs:
- Ubiquitous – SATA ports are standard on virtually all modern PCs
- Cost-effective – SATA SSDs are inexpensive compared to other interfaces
- Proven reliability
- Good max throughput of 600MB/s with SATA III
- Older technology with lower maximum throughput than newer interfaces
- SATA ports are limited to 1 per device, may require port multiplier for additional SSDs
For most basic consumer needs, SATA SSDs provide the best balance of price and performance. The ubiquity of SATA makes it easy to add an SSD to desktops and laptops. For high performance needs, other faster interfaces may be required.
PCIe and NVMe SSDs connect directly to PCI Express lanes in a computer system for much higher throughput. Rather than using the SATA protocol, PCIe SSDs use the NVMe protocol designed specifically for SSDs. Here are some of the key differences of PCIe/NVMe SSDs:
- Very high throughput – NVMe SSDs reach over 3,000 MB/s
- Low latency for fast access
- Multiple PCIe lanes allow scaling performance
- Higher cost per GB than SATA SSDs
- Require motherboard with NVMe/PCIe support
For high performance needs such as gaming, content creation, video editing and more – PCIe/NVMe SSDs are the best choice. The blazing fast speeds justify the higher costs for these demanding workloads. Compatibility needs to be verified with the PC/motherboard model before selecting a NVMe drive however.
M.2 SSDs use a new form factor designed for ultrabooks and other small footprint computing devices. Rather than the traditional box with SATA/power connectors, M.2 SSDs plug directly into an M.2 slot on the motherboard. The key advantages of M.2 SSDs include:
- Small footprint -ideal for thin mobile devices
- Streamlined integration by plugging directly into motherboard
It’s important to note that M.2 drives can use either SATA or PCIe/NVMe interfaces. An M.2 slot connection doesn’t guarantee higher performance – it only describes the physical connector. When selecting an M.2 drive, you still need to verify whether it is SATA or PCIe based.
The U.2 interface (formerly known as SFF-8639) was designed primarily for enterprise and data center usage. U.2 uses a new connector instead of regular SATA ports, but still uses the SATA protocol and wiring for a maximum throughput of 600 MB/s. The main advantages of U.2 include:
- Designed for easy drive “hot-swapping” in servers
- Faster performance than mSATA or eMMC SSDs
For the majority of client computing needs, standard M.2 and 2.5″ SATA or PCIe SSDs are preferable over the more niche U.2 interface. However, for enterprise servers that need to hot swap drives, a U.2 SSD would be beneficial over standard SATA connections.
CFexpress is one of the newest SSD interfaces on the market designed for high-end media recording and playback. The key highlights of CFexpress include:
- Very high throughput – up to 8GB/s theoretical max
- Optimized for media creation workflows
- Backwards compatible with XQD
CFexpress shows great promise for future media capture devices, but presently has very limited adoption. The few devices currently supporting CFexpress are premium high megapixel cameras and media recorders. The high cost and limited accessibility of CFexpress means most consumer computing devices are better served by PCIe/NVMe SSDs today. But longer term, CFexpress could replace SD cards as the dominant storage media for professional media applications.
eMMC / UFS
eMMC (embedded MultiMediaCard) and UFS (Universal Flash Storage) are integrated storage solutions commonly found in smartphones and tablets. Rather than discrete modules, these technologies integrate NAND flash memory directly onto the device’s motherboard:
- Highly integrated for small form factors
- Lower costs than removable storage media
- Not user upgradable or replaceable
- Soldered to device – not transferable
For mobile and embedded computing applications, eMMC and UFS provide reliable built-in storage at low costs. But for general computing needs, removable and upgradeable SSDs are preferred.
Choosing the Right SSD Interface
With so many available options, selecting the right SSD interface boils down to matching performance needs to budget. Here are some general guidelines:
- Entry-level consumer SSD upgrade – SATA III SSD
- High performance for gaming/workstations – PCIe NVMe SSD
- Ultrabook/space-constrained PC – M.2 SATA or PCIe SSD
- Smartphones/tablets – eMMC or UFS integrated storage
- Media recording and playback – CFexpress
- Enterprise servers – U.2 SSDs
Interfaces with the same connector type can still have vastly different performance – always verify whether it is SATA or PCIe based. Also consider physical size constraints depending on the target device or computer case space. With SSD costs declining rapidly, the tremendous speed boost over HDDs makes them one of the most impactful PC upgrades today. Carefully selecting the right interface ensures you are maximizing the full potential of your shiny new solid state drive.
SSD Interface Comparison Table
|Interface||Max Sequential Read||Max Sequential Write||Use Cases|
|SATA III||600MB/s||600MB/s||Entry-level consumer SSD, HDD replacement|
|PCIe Gen3 x4 / NVMe||3,500MB/s||3,000MB/s||High performance PCs and workstations|
|PCIe Gen4 x4 / NVMe||7,000MB/s||4,000MB/s||Extreme performance PCs, servers|
|CFexpress||8,000MB/s||4,000MB/s||High-end media recording and playback|
|UFS 2.1||850MB/s||170MB/s||Smartphones, tablets, embedded systems|
|eMMC 5.1||400MB/s||260MB/s||Budget smartphones, tablets, embedded systems|
SSD technology provides tremendous performance benefits over traditional hard disk drives. But realizing the full potential requires careful selection of the appropriate interface for your specific needs and budget. SATA continues to offer a great value for basic system upgrades, while PCIe NVMe delivers blistering speeds for high demand applications. Keeping up with the latest options ensures your next SSD purchase provides many years of fast and reliable service. With broad industry support driving new innovations, the future remains bright for SSD interface improvements across consumer and enterprise computing.