Each capacity of the 840 Evo is advertised as having 540 MB/s read speeds. As for the write speeds, it depends on the size of the drive. The 120 GB model allegedly has a write speed of 410 MB/s, three times as fast as its predecessor, and the others (250 GB to 1 TB) write at 520 MB/s.
BuildThe Samsung 840 Evo is a 2.5" drive with a SATA III interface (6 Gbps). Its 7-mm-thin body is lighter than most, weighing 44 grams, an undeniable plus for laptop owners.
Samsung used its own MEX Controller, which is composed of three ARM Cortex-R4 cores clocked at 400 MHz, whereas the previous MDX Controller in the Samsung 840 was clocked at 300 MHz. The TLC NAND uses a 19 nm process.
Just as SanDisk did with the Extreme II and Ultra Plus, Samsung used a buffer system (TLC flash simulated as SLC, with one bit instead of three) to boost the write speeds. The buffer size varies depending on the SSD's capacity: 3 GB for the 120 and 250 GB, 6 GB for the 500 GB, 9 GB for the 750 GB, and 12 GB for the 1 TB.
To protect data against temperature increases, Samsung also included a system that curbs the read/write speeds in order to keep the drive under a certain temperature, or at least to limit its overheating.
Data Transfer Speeds
File Transfers (Photos, Videos...): Sequential Speeds
The speeds Samsung advertises are accurate when it comes to large files. We measured 503 MB/s read and 416 MB/s write speeds. The Samsung 840 Evo gets better speeds than last year's 840, but it's still a good notch below the 840 Pro 256 GB, our current record holder.
That's with files smaller than the buffer. If you transfer files over 3 GB in size, however, the transfer rate plummets to 260 MB/s—the same as last year's 840.
Accessing Programmes: 4K Random Access
Small files are handled better than large files. With 64 MB/s writes on 4K files and 33 MB/s reads, it's on par with the outstanding Samsung 840 Pro.
Samsung SSD Magician
Also in the box is a CD for SSD Magician, or you can download it from Samsung's website. This is an intuitive programme that offers a variety of functions, such as system info, benchmarking, SSD/OS performance optimisation, firmware updates, secure deletion and over-provisioning.
In the CD you'll also find a cloning programme for transferring data from another drive to the SSD. It's quick and easy to do, perfect for when you want to replace your old drives!
- 506 MB/s reads on large files
- 416 MB/s writes on large files
- Lightweight, perfect for a notebook
- Samsung SSD Magician software is handy and intuitive
- TLC flash memory is theoretically three times less long-lasting than MLC
- Write speed drops to 260 MB/s on files over 3 GB
The Samsung 840 Evo definitely isn't the best SSD we've reviewed, but it's relatively fast and lightweight and it costs less than most higher-performance drives. The biggest drawbacks are that it uses TLC flash memory, which doesn't last as long as MLC, and only has a 3-year warranty where high-end models are usually guaranteed 5 years.