Solid-state drives (SSDs) that use the SATA interface and are sized at 2.5 inches or 3.5 inches provide fast data transfer speeds and high performance compared to traditional hard disk drives (HDDs). SATA SSDs are a popular storage choice for both consumer and business use thanks to their speed, durability, and decreasing cost over time.
Quick Answers
Here are some quick answers to common questions about 3.5″ SATA SSD speeds:
- 3.5″ SATA SSDs can deliver sequential read/write speeds up to 550/520 MB/s.
- Random read/write speeds can reach up to 100,000 IOPS.
- Their interface uses the SATA III 6Gb/s standard, so they are compatible with most modern systems.
- Real-world speeds vary based on the drive’s controller, NAND flash memory, and firmware optimizations.
- 3.5″ form factor SATA SSDs are faster than hard drives but slower than M.2 NVMe SSDs.
SATA Interface Overview
SATA stands for Serial Advanced Technology Attachment and refers to the interface protocol used to connect storage devices like HDDs, SSDs, and optical drives to a computer’s motherboard. The SATA interface uses point-to-point serial connections rather than the older parallel connections used by ATA interfaces. Here are some key facts about SATA:
- Introduced in 2003 as the replacement for the Parallel ATA (PATA) standard.
- Defines physical connection cables/connectors and logical signaling protocols.
- Transfers data in serial fashion one bit at a time rather than in parallel.
- First generation SATA 1.0 supported speeds up to 1.5Gbps.
- Current generation SATA III runs at maximum speed of 6Gbps.
- Hot swappable – devices can be connected and disconnected while system is running.
- Thinner cables allow improved airflow and organization in computer cases.
The SATA interface has gone through several major revisions since its introduction in 2003. Each version increased the maximum theoretical transfer speeds as follows:
| SATA Version | Max Transfer Speed |
|---|---|
| SATA I | 1.5Gbps |
| SATA II | 3Gbps |
| SATA III | 6Gbps |
Current SATA III speeds of up to 6Gbps provide plenty of headroom for even the fastest modern SSDs. The SATA interface is also backward compatible, so SATA III SSDs will work with older SATA I and SATA II ports and cables, albeit at reduced speed.
3.5-inch SATA SSD Form Factor
3.5-inch drives are designed to fit in standard drive bays and racks used for desktop PCs. Some key characteristics of 3.5-inch SATA SSDs include:
- Dimensions of 101.6 x 146 mm – same as 3.5″ hard drives.
- Requires a power cable and data cable to operate.
- Typically housed in metal enclosures for durability.
- Can reach capacities up to 16TB for SSDs.
- Heavier than 2.5″ SSDs due to larger size and enclosure.
- Compatible with common 3.5″ drive bay mounts and racks.
- Used primarily for desktop PCs instead of laptops.
The larger physical size of 3.5-inch SATA SSDs allows for greater NAND flash capacity than smaller form factors like M.2. While they do not reach the raw speeds of M.2 NVMe drives, 3.5″ SATA SSDs provide a good balance of speed, capacity, and affordability.
Compared to 2.5-inch SATA SSDs
Both 2.5-inch and 3.5-inch drives utilize the same SATA interface, but in different physical sizes. Here’s a brief comparison:
- 2.5″ SSDs are smaller and lighter, designed for laptops.
- 3.5″ SSDs can fit more NAND flash for greater capacities.
- 2.5″ drives get power over SATA from laptops.
- 3.5″ drives need an additional power cable from PSU.
- 2.5″ maxes out around 2TB capacity for SATA SSDs.
- 3.5″ support up to around 16TB SATA SSD capacities.
- Both run at the same SATA III speeds up to 6Gbps.
While they both use the SATA III interface, the larger physical size of 3.5-inch SSDs allows them to reach much greater NAND flash storage capacities. However, 2.5-inch SSDs are more compact and better suited for laptops.
3.5-inch SATA SSD Speed
When it comes to speed, 3.5″ SATA SSDs deliver excellent performance – much faster than HDDs but below cutting-edge NVMe SSDs. The sequential read/write and random read/write speeds are key metrics to look at.
Sequential Read and Write Speeds
Sequential speeds measure how fast a drive can read and write large, contiguous blocks of data. This simulates file transfers and other large operations.
- Top 3.5″ SATA SSDs reach up to 550 MB/s read and 520 MB/s write.
- Budget models may have 350-400 MB/s sequential speeds.
- For comparison, HDDs max out around 200 MB/s sequential.
- NVMe SSDs exceed 3,500 MB/s, but are more expensive.
While not as fast as NVMe, even budget 3.5″ SATA SSDs are at least twice as fast as hard drives for sequential transfers. Faster models nearing the SATA III limit provide excellent speed for large file operations.
Random Read and Write Speeds
Random access speeds measure how quickly a drive can retrieve and write small, non-contiguous blocks of data. This affects boot times and general snappiness.
- Top SATA SSDs exceed 90,000 random read IOPS.
- Write IOPS typically range from 50,000 to 90,000.
- Budget SATA SSDs may have 15,000-30,000 IOPS.
- A hard drive does only a few thousand IOPS typically.
While the SATA interface limits their overall throughput compared to NVMe, 3.5″ SATA SSDs remain very responsive thanks to high random IOPS. Even entry-level SATA SSDs are far ahead of HDDs for random performance.
Real-World Speed Analysis
Looking beyond just the theoretical interface limits and advertised manufacturer specs, real-world testing reveals the true performance among various SATA SSD models. Factors like the drive’s controller, NAND flash grade, and firmware optimizations all impact real-life speed.
For example, the Samsung 870 QVO is a very popular and affordable high-capacity 3.5″ SATA SSD. Testing shows its real-world speeds measure roughly:
- 560 MB/s sequential read
- 530 MB/s sequential write
- 98,000 random read IOPS
- 88,000 random write IOPS
This aligns closely with Samsung’s claimed specs of up to 560/530 MB/s and random IOPS in the 90-98,000 range. The 870 QVO provides excellent real-world SATA III performance.
On the other hand, the Crucial MX500 is slightly slower in testing:
- 564 MB/s sequential reads
- 510 MB/s sequential writes
- 91,000 random read IOPS
- 84,000 random write IOPS
While still very fast, independent testing shows the MX500 hits slightly below its advertised 560/510 MB/s and 95,000 IOPS. This demonstrates how drive components impact real-speed.
SATA SSDs vs. NVMe SSDs
When comparing 3.5″ SATA SSDs to faster M.2 NVMe SSDs, the performance differences become more apparent:
| Spec | SATA SSD | NVMe SSD |
|---|---|---|
| Interface | SATA III – 6Gbps | PCIe 3.0 x4 – 32Gbps |
| Sequential Read | Up to 550 MB/s | Over 3500 MB/s |
| Sequential Write | Up to 520 MB/s | Over 3000 MB/s |
| Random Read IOPS | Up to 100,000 | Up to 750,000 |
| Random Write IOPS | Up to 90,000 | Up to 750,000 |
While 3.5″ SATA SSDs are plenty fast for most everyday use, cutting-edge NVMe M.2 drives provide several times higher throughput and IOPS. Their greater speeds are most noticeable for very large file transfers or heavy multitasking.
When to Choose NVMe Over SATA
For most routine desktop PC tasks, SATA SSDs provide good enough performance. NVMe SSDs are best leveraged in these scenarios:
- Working with very large files like high-res video
- Running apps that need fast sequential reads/writes
- Increasing multitasking limits
- Maxing out gaming frame rates
- Future-proofing a system for next-gen apps
Unless you regularly work with 100+ GB files or run heavy workstation apps, a SATA SSD will likely satisfy your performance needs at a lower cost. NVMe excels at breaking the SATA bottleneck for transfer-intensive tasks.
Conclusion
3.5-inch SATA SSDs deliver excellent real-world performance – much faster than hard drives but below cutting-edge NVMe SSDs. Top sequential speeds exceed 550/500 MB/s reads/writes, while random IOPS can hit 100,000. These speeds allow fast boot times, responsive system performance, and snappy application launches for most typical desktop PC tasks.
While NVMe SSDs boast up to 5x the throughput and IOPS, they carry a price premium. SATA SSDs provide a great blend of speed, capacity, affordability, and wide compatibility. Unless you regularly transfer 100GB+ files or run heavily multithreaded apps, a quality 3.5″ SATA SSD will meet the performance needs of most users.