Hard drives come in two main sizes – 2.5″ and 3.5″. The 3.5″ size has traditionally been used for desktop PCs, while the smaller 2.5″ size is common in laptops. With the rise of small form factor and home theater PCs, the 2.5″ hard drive has become an attractive option for rigs where space is limited.
Installing a 2.5″ hard drive in a desktop PC is possible but involves some considerations around compatibility, mounting, cabling, BIOS/OS setup, and performance factors. In this guide we’ll provide a comprehensive overview of the key steps involved in installing a 2.5″ hard drive in a desktop PC, looking at the pros and cons, and examining some sample usage scenarios.
Benefits of 2.5″ Hard Drives
2.5″ hard drives, also known as laptop hard drives, have several advantages over larger 3.5″ desktop hard drives. Their smaller physical size makes them more portable and convenient to use (Source). 2.5″ drives can be powered directly via a USB cable, making them very simple to connect externally. Their compact form factor also allows them to fit in smaller PC cases or enclosures.
In addition to their smaller size, 2.5″ hard drives consume less power than 3.5″ drives. Their lower power draw makes them well-suited for mobile devices and small form factor systems where power efficiency is important. The reduced power consumption also results in less heat generation, allowing 2.5″ drives to run cooler and quieter (Source). This can be advantageous in media centers and home theater PCs where noise is a concern.
Lastly, the compact size and lower weight of 2.5″ drives also allow them to better withstand shocks, vibrations, and movement compared to larger 3.5″ hard drives. Their resilience makes them suitable for external portable storage and use in laptops that are prone to being bumped or moved while in use (Source). Overall, 2.5″ drives offer greater flexibility, efficiency, durability, and convenience compared to traditional 3.5″ desktop hard drives.
Potential Drawbacks
One of the main potential drawbacks of using a 2.5″ hard drive in a desktop is that they typically have lower capacities than 3.5″ drives. According to this source, 3.5″ HDDs generally have a much greater range of storage capacities available, with high capacity models going up to 10TB or more. In contrast, most 2.5″ HDD models max out at 2TB. For users who need a lot of storage space, the capacity limitations of 2.5″ drives could be a significant downside.
Additionally, 2.5″ HDDs often have a higher cost per gigabyte compared to 3.5″ models. As noted in this Reddit discussion, the smaller size and form factor of 2.5″ drives comes with a price premium. Users looking to maximize storage capacity per dollar spent may want to opt for cheaper high capacity 3.5″ HDDs instead. However, 2.5″ drives provide more flexibility for small form factor and portable builds where physical space is limited.
Compatibility Factors
When considering using a 2.5″ hard drive in a desktop computer, you’ll want to ensure compatibility with the motherboard and power supply.
For the motherboard, most modern desktop motherboards have standard SATA connectors that a 2.5″ drive can plug right into. The physical size doesn’t matter, as long as the connector type matches up. Just make sure your motherboard has an open SATA port to connect the 2.5″ drive to.
In terms of the power supply, you’ll need to check that it has a spare SATA power connector. Most modern power supplies have several SATA power cables already in place for 3.5″ hard drives. As long as you have an open SATA power connector, you can easily hook up the 2.5″ drive.
The 2.5″ form factor gets power and transfers data just like a 3.5″ hard drive. So as long as your motherboard has SATA ports and the power supply has SATA power cables available, compatibility should not be an issue.
Mounting the Drive
One of the key differences when installing a 2.5″ hard drive in a desktop PC is how the drive will be mounted. 3.5″ desktop hard drives use standardized mounting screw positions, while 2.5″ drives have less standardized mounts.
There are a couple options for securely mounting a 2.5″ drive in a desktop PC:
Bracket Adapters – There are inexpensive ($5-10 USD) metal brackets that adapt a 2.5″ drive to fit in a standard 3.5″ drive bay. The drive slides into the bracket which has standard screw holes. This is the easiest mounting option. As noted in How to install an SSD in a desktop PC, these bracket adapters “make installation super easy.”
Custom Mounting – For a cleaner look, the 2.5″ drive can be directly mounted into the case. This may require drilling custom screw holes and devising a mounting plan specific to the case. If there is not space behind the motherboard tray, double-sided tape or adhesive can also be used to securely mount the 2.5” drive.
Connecting Cables
When connecting a 2.5″ hard drive to a desktop computer, you will need two cables – a SATA data cable and a power cable or adapter. The SATA data cable is used to transfer data between the drive and the computer’s motherboard. Most modern motherboards have SATA ports, so you can connect a SATA cable directly from the drive to the motherboard. High quality SATA cables like the StarTech SATA to USB Cable can provide faster data transfer speeds up to 6 Gbps (Amazon).
For power, you have two options. Many power supplies have extra SATA power connectors that you can use. If not, you will need a SATA power adapter cable that draws power from a Molex or SATA connector and converts it to the small form factor SATA power connector for a 2.5″ drive. There are many options for SATA power adapter cables available on Amazon.
Make sure to get cables that are long enough to route cleanly inside your computer case. With the right SATA data and power cables, connecting a 2.5″ hard drive to a desktop PC is straightforward.
BIOS/OS Setup
To get a 2.5″ hard drive working properly in a desktop computer, you may need to enable AHCI mode in the BIOS. AHCI (Advanced Host Controller Interface) allows the operating system to take full advantage of the capabilities of SSDs and HDDs. Most modern motherboards have this option present in the BIOS.
To enable AHCI mode:
- Restart your computer and press the key to enter the BIOS, often Delete or F2.
- Navigate to the “Advanced” tab and look for the setting related to SATA or AHCI mode.
- Change the setting from IDE to AHCI.
- Save changes and exit the BIOS.
After enabling AHCI, you’ll need to initialize and format the 2.5″ drive so your operating system can access it. This involves the following steps:
- In Windows, open Disk Management.
- Right click on the unallocated space on your new drive and select “New Simple Volume”.
- Follow the prompts to initialize the drive and format it with your desired file system, likely NTFS.
Now your 2.5″ drive will show up in File Explorer ready for use. Refer to this Seagate article for more details on the process.
Performance Factors
When considering the performance of 2.5″ hard drives, two key factors are RPM speed and cache size. Most 2.5″ hard drives have spindle speeds between 5400-7200 RPM, with 7200 RPM generally providing better performance for things like loading games, applications, or the operating system [1]. The linear velocity at the edge of a 2.5″ 7200 RPM drive is about 1,410 inches per second.
In addition to RPM speed, the cache size also impacts performance. 2.5″ hard drives often have 8MB, 16MB, 32MB or 64MB of cache. More cache can allow the drive to store frequently accessed data and improve read/write speeds, resulting in snappier performance. Overall, a 7200 RPM 2.5″ drive with a 32MB or 64MB cache will provide a good blend of speed and capacity for desktop usage.
Usage and Applications
2.5″ drives have some advantages and disadvantages compared to 3.5″ drives when used as either a boot drive or a storage drive:
As a boot drive, 2.5″ drives have the benefit of being smaller, lighter, and drawing less power, making them ideal for laptops and small form factor desktops. However, 2.5″ drives tend to have lower maximum capacities than 3.5″ drives. Many desktop PC cases cannot accommodate mounting a 2.5″ drive, requiring an adapter.
For a storage drive, such as in a media server, 3.5″ drives are generally preferred due to their higher capacities and better price per gigabyte. However, 2.5″ drives can work well for cheaper, lower capacity storage needs. Their smaller size allows fitting more drives into a compact server chassis. Noise and heat output is lower with 2.5″ drives.1
In summary, 2.5″ drives work best as boot drives where small size is needed, while 3.5″ drives excel as high capacity storage drives. 2.5″ drives can serve lighter storage needs in space constrained setups due to their compact size.
Summary
Installing a 2.5″ hard drive in a desktop PC is generally a straightforward process. The main considerations are ensuring your PC has the proper internal connectivity for a smaller drive form factor, and taking the right steps for mounting the drive and setting up the BIOS and OS.
There are several benefits to using a 2.5″ drive in a desktop build. The smaller size allows more flexible mounting options, like installing in a 3.5″ bay with an adapter bracket or even mounting directly to the case interior with adhesive pads or velcro. 2.5″ drives run cooler, use less power, and generate less noise since they don’t require as much spin speed for performance. They are ideal for certain use cases like boot drives or extra storage in space-constrained builds.
With the right cabling and setup, a 2.5″ drive can deliver adequate performance for many desktop uses. Just be sure your motherboard has an available SATA port and that your PC case can properly accommodate the drive’s physical size. Take care when selecting your mounting method to ensure the drive stays securely in place.
