If our lack of reviews didn't tell, there have been few notable SSD versions this year, with OCZ's internal Vertex 450 and the Marvell 88SS9187-based SanDisk Extreme II being the main exceptions. This is much less eventful than in previous years and in 2012 alone OCZ brought Vector and Vertex 4, Crucial Adrenaline, the Intel SSD 520 series and countless other SandForce SF-2281 drives.
Samsung's contribution to the enthusiastic flash drive market may deserve special recognition as its 840 Pro series with 21nm toggle NAND chips arrived before the holidays, wiping out most of the competition. Though it's been a while and OCZ's flagships can certainly start a fight, we still prefer Samsung's product – at least in part because the 512GB 840 Pro lasted a year of service in my office PC.
Flash performance and endurance are a sensitive issue, but we're confident the SSD 840 Pro will remain one of the best in both categories. So we knew Samsung really had to make things better. It was just about how and how the company revealed that part at its annual global summit, of course. Samsung has focused on solving Flash's biggest victims: size and affordability.
The new SSD 840 Evo range includes models from 120GB to 1TB, with the largest costing just $ 0.65 per gigabyte thanks to the use of TLC NAND. Meanwhile, the Evo drives promise solid performance thanks to several sophisticated features, including an SLC-based write cache ("TurboWrite") and a secondary caching system called RAPID (Real-Time Accelerated Processing of I / O Data) in the System memory is immersed.
Samsung 840 Evo 1 TB & 250 GB in detail
To be clear, the SSD 840 Evo is still aimed at performance improvers, while the older SSD 840 Pro series is mostly aimed at enthusiasts willing to pay for the best performance. Equipped with the MEX controller (SATA 3.1) from Samsung, the series offers five capacities: 120 GB (USD 109), 250 GB (USD 183), 500 GB (USD 370), 750 GB (USD 530) and 1 TB (650 USD). The drives have a slim 2.5-inch design, are 100.08 x 69.85 x 7.11 mm and weigh up to 54.4 g.
The 120 GB model offers read and write speeds of 540 MB / s and 410 MB / s, which is more than claimed by the SSD 840 Pro of the same capacity, while the 250 GB, 500 GB, 750 GB and 1 TB can reach 540 MB / s and 520 MB / s. All of them feature Samsung's 19nm 3 bpc TLC toggle DDR 2.0 NAND flash memory. You can find two of these chips in the 120 GB and 250 GB versions, four in the 500 GB unit and double in the 750 GB / 1 TB variants.
TurboWrite – one of the mentioned caching functions – assists the Evo's TLC memory in providing MLC-like performance by using a small portion of each TLC NAND chip as an SLC write buffer. The 120 GB and 250 GB Evo drives have a 3 GB TurboWrite buffer that increases by 3 GB for each subsequent model, with 1 TB having a 12 GB buffer.
The idea is to write data to the SLC buffer before quickly moving it to the TLC memory. If you write a file that is larger than the buffer or the buffer becomes full and is not cleared in time, the data will be written directly to the slower TLC memory. For light use, the 120GB and 250GB models should be fine. However, if you consistently write more than 3GB of data, you may experience a slowdown.
For example, the 250 GB Evo's sequential write performance is around 500 MB / s when using TurboWrite, but drops below 300 MB / s when the buffer is full. Most of the time, this isn't a problem for the 1TB drive as its 12GB buffer should handle most conditions.
Just like the MDX of the SSD 840 Pro, the Samsung MEX controller has a Cortex R4 processor with three cores, with the exception that the frequency of the three cores has been increased from 300 MHz to 400 MHz. SATA 3.1 support is also available, queuing TRIM commands – something we first experienced on the SanDisk Extreme II.
The Evo series can also access up to a gig of system memory with their RAPID DRAM caching feature, which is only available for these drives and which supposedly increases read performance by storing frequently accessed data in your RAM – something we do we will examine it more closely on the next page.
While the SSD 840 Pro series is available in 128GB, 256GB, and 512GB models, the Evo range is scaled down to 120GB, 250GB, etc. to accommodate the use of TLC storage. In addition, each drive comes with a healthy cache: 256 MB for the 120 GB and 250 GB drives, 512 MB for the 500 GB version, and a massive 1 GB for the 750 GB and 1 TB drives. Models.
Interestingly, Samsung doesn't claim how many terabytes of data can be written before the drives expire and instead just backed them up with a three-year warranty.