Solid state drives (SSDs) have become increasingly popular in recent years as an alternative to traditional hard disk drives (HDDs). SSDs offer much faster read and write speeds, lower latency, better reliability, and quieter operation compared to HDDs. However, SSDs have traditionally been available in smaller form factors like 2.5 inches, while 3.5 inch drives have been dominated by HDDs.
This leads to a common question – do 3.5 inch SSDs exist? The short answer is yes, 3.5 inch SSDs are available, but they remain far less common than 2.5 inch SSDs. In this article, we’ll take a deeper look at 3.5 inch SSD technology and options.
What are the typical sizes for SSDs?
2.5 inches has been the most common form factor for SSDs since their mainstream introduction in the late 2000s. The 2.5 inch size was adopted from the existing standard for laptop hard drives, allowing SSDs to be easily integrated into laptops as a replacement for HDDs. The 2.5 inch form factor remains popular today for laptops, desktops, and servers.
More recently, smaller mSATA, M.2, and gumstick SSDs have become popular in ultrathin laptops and tablets where space is at a premium. These smaller SSDs can be installed directly on the motherboard, reducing wiring and space requirements.
On the larger end, 3.5 inch SSDs do exist, but have not seen as much adoption. 3.5 inch hard drives have traditionally been used in desktop PCs and servers where large capacity is important. While 3.5 inch SSDs are available up to around 16TB, most users still favor the lower cost per GB of high capacity HDDs for mass storage.
Are there any advantages to a 3.5 inch SSD form factor?
Here are some of the potential advantages to using a 3.5 inch SSD form factor:
- Higher capacity options – 3.5 inch bay slots allow for larger SSDs to be installed. While 2.5 inch SSDs max out around 8TB currently, 3.5 inch SSDs are available up to 16TB.
- Better cooling – The larger surface area of a 3.5 inch SSD relative to a 2.5 inch SSD allows for more effective cooling. This improved cooling can potentially reduce throttling.
- Backplane compatibility – 3.5 inch SSDs can be used to replace 3.5 inch HDDs without any modifications to drive bays or backplanes in desktop PCs and servers.
- Power and cable compatibility – 3.5 inch SSDs can tap into the existing power and SATA cables used for 3.5 inch HDDs.
For these reasons, someone looking to upgrade an existing desktop or server from HDDs to SSDs may prefer dropping in 3.5 inch SSDs to take advantage of the extra capacity and existing infrastructure support.
What are the downsides to 3.5 inch SSDs?
Here are some potential disadvantages or downsides to be aware of with 3.5 inch SSDs:
- Higher cost per GB – Larger SSDs generally have a higher cost per GB compared to smaller SSDs with the same technology. So a 3.5 inch SSD will have a higher price for an equivalent capacity compared to a 2.5 inch SSD.
- Underutilization – Unless you truly need the extra capacity, a 3.5 inch SSD may be overkill and you won’t fully utilize the extra capacity. A smaller 2.5 inch SSD may be more cost-efficient.
- Limited selection – The market selection for 3.5 inch SSDs is smaller compared to the abundant options for 2.5 inch SSDs. Fewer brands produce 3.5 inch SSD models.
- Form factor limitations – 3.5 inch bays are less common in smaller PCs. You won’t be able to install a 3.5 inch SSD in a laptop or ultra-small PC with only M.2 or 2.5 inch drive support.
For many PC builds, a 2.5 inch or M.2 SSD will be perfectly sufficient and the most cost-effective option. Carefully consider if you can fully take advantage of the benefits of a 3.5 inch SSD before opting for one.
What interface options are available for 3.5 inch SSDs?
3.5 inch SSDs are available with the following interface options:
- SATA 3 – The most common interface for 3.5 inch SSDs is SATA 3 (SATA 6Gb/s). SATA 3 offers up to 600MB/s bandwidth, compatible with existing SATA backplanes and cables.
- SAS – For enterprise/server use, 3.5 inch SSDs are available with 12Gb/s SAS interfaces. SAS offers more bandwidth and advanced capabilities compared to SATA.
- NVMe – For the highest performance, NVMe 3.5 inch SSDs connect via PCIe instead of SATA. NVMe offers massive bandwidth – up to 3.5GB/s over 4 lanes.
For typical desktop PC use, a SATA 3 SSD is recommended for the best value. SAS and NVMe SSDs offer more niche benefits at a higher price point. Be sure your PC setup supports NVMe before getting an NVMe 3.5 inch SSD, as it requires NVMe cabling and motherboard headers.
What capacities are available for 3.5 inch SSDs?
Here is an overview of the typical capacity options available for 3.5 inch SSDs:
| Capacity | Type |
| 240-960GB | Consumer SATA 3 SSDs |
| 2-8TB | Prosumer/Enterprise SATA 3 SSDs |
| 4-16TB | Enterprise SAS/NVMe SSDs |
As you can see, 3.5 inch SSD capacities range from 240GB models designed for boot purposes up to massive 16TB enterprise drives. For most home builds, a 1-4TB SATA 3 SSD should be plenty.
In comparison, 2.5 inch SSD capacities top out around 8TB currently. So if you need a very high capacity SSD over 8TB in a single drive, the 3.5 inch form factor is required.
What types of NAND flash do 3.5 inch SSDs use?
3.5 inch SSDs utilize the same types of NAND flash memory as smaller SSDs. Some of the common NAND flash options include:
- TLC – Triple Level Cell flash offers a good balance of cost and performance for consumer SSDs. Each memory cell stores 3 bits of data.
- QLC – Quad Level Cell maximizes density by storing 4 bits per cell, but has slower write speeds. Common for high capacity consumer SSDs.
- MLC – Multi-Level Cell flash is less dense than TLC but offers better endurance and performance. Used for enterprise SSDs.
- SLC – Single Level Cell stores just 1 bit per cell. It provides the fastest performance and highest endurance ratings, but is expensive.
The best value 3.5 inch SSDs designed for home builds typically use 64-layer TLC NAND flash. This provides great read/write speeds around 550/520 MB/s and endurance ratings of 0.3-1 drive writes per day.
What controller and caching options are used?
3.5 inch SSDs aimed at consumers generally use mid-range controllers from companies like Phison, Silicon Motion, Marvell, etc. These controllers paired with a small DRAM cache provide excellent performance for the price. Here are some specifics:
- Phison E12 and Silicon Motion SM2262/2263 controllers are popular for budget and mainstream SATA 3 SSDs.
- Higher-end options may use Phison E12S, SM2262EN or Marvell 88SS1092 controllers.
- NVMe 3.5 inch SSDs typically utilize high-end Phison, Marvell, Silicon Motion or Microsemi controllers.
- DRAM cache sizes range from 256MB up to 2GB depending on model.
Enterprise 3.5 inch SSDs designed for intense workloads utilize more robust controllers and larger DRAM caches to deliver optimal performance and endurance.
Overall the controller and cache choices largely mirror what you’ll find on 2.5 inch SSDs – just scaled up for the 3.5 inch form factor.
What are typical performance specs?
Here are the typical performance specs you can expect from mainstream 3.5 inch SATA and NVMe SSDs for desktop PC use:
| Interface | Read Speed | Write Speed | IOPS |
| SATA 3 | 550MB/s | 520MB/s | Up to 97K |
| NVMe | 3,500MB/s | 3,000MB/s | Up to 750K |
As you can see, NVMe 3.5 inch SSDs offer tremendous speed advantages over SATA models. However, for general desktop use, a SATA 3 SSD still provides excellent performance.
Enterprise 3.5 inch SSDs designed for servers and data centers are optimized for high queue depth workloads and can reach up to 1 million IOPS for both reads and writes.
How much power do 3.5 inch SSDs use?
3.5 inch SSDs draw similar power to 2.5 inch SSDs, typically under 10W even for max performance under load. Here are some typical power ratings:
- Idle or Low Load: 2-3W
- Sustained Reads: 2-4W
- Sustained Writes: 4-8W
- Peak Power: up to 10W
For comparison, a hard drive might use 5-15W depending on its rotational speed and workload. So SSDs consume much less power and run cooler overall.
NVMe SSDs tend to have slightly higher power draw compared to SATA models since PCIe provides more power over the cable. But in either case, SSD power efficiency is excellent.
What temperatures do 3.5 inch SSDs operate at?
SSDs run reliably at a wide range of temperatures thanks to their solid state design. Here are the typical operating and storage temperatures:
- Operating Temperatures: 0°C to 70°C
- Short Term Max (tested): Up to 85°C
- Storage Temperatures: -40°C to 85°C
Most SSDs utilize thermal throttling to automatically slow down if temperatures approach the upper limits. But cooling is generally not a major concern with SSDs under normal workloads.
The larger metal casing of a 3.5 inch SSD compared to a 2.5 inch drive can further aid passive cooling capabilities. Overall, SSDs run much cooler than traditional hard drives.
What are typical warranty periods?
Consumer 3.5 inch SSDs tend to come with 3 to 5 year limited warranties from the manufacturer. This covers you against defects and premature drive failure. Here are some common warranty periods:
- Budget SSDs: 3 years
- Mainstream SSDs: 5 years
- High-end SSDs: 5 years or more
Many SSD warranties are based on TBW (terabytes written) endurance ratings. Once you exceed the TBW rating, the warranty coverage expires. So higher endurance SSDs usually come with longer warranties.
For enterprise and server use, 3.5 inch SSD warranties may extend to 5-7 years with very high endurance ratings, demonstrating rated reliability under intense workloads.
Conclusion
In summary, 3.5 inch SSDs certainly exist and can offer compelling benefits like massive capacity and easy integration into desktops over traditional hard drives. However, for most everyday users, the extra capacity and size isn’t necessary and smaller form factor SSDs like M.2 and 2.5 inches offer the best value.
3.5 inch SSD adoption has been slower versus smaller form factors, but steadily growing thanks to higher density NAND flash enabling bigger capacities. As 3.5 inch SSD prices continue to come down, their usage will likely keep increasing in desktops and data centers moving forward.