Data Journey

SSD Comparison: Differences between Samsung 850 Pro / EVO and 840 Pro / EVO Series

Both SSD series 840/850 by Samsung, in the versions EVO / Pro, have quite similar reading and writing performance values (except for the 128GB models). Nevertheless, they differ especially in the price. This raises the legitimate question: How this price difference comes about and what am I supposed to buy?

Sequential Read

Reading rates 128 GB 256 GB 512 GB 750 GB 1000 GB
Samsung 850 Pro 550 MB/s 550 MB/s 550 MB/s 550 MB/s
Samsung 850 EVO 540 MB/s 540 MB/s 540 MB/s 540 MB/s
Samsung 840 Pro 530 MB/s 540 MB/s 540 MB/s
Samsung 840 EVO 540 MB/s 540 MB/s 540 MB/s 540 MB/s 540 MB/s

Sequential Write

Writing rates 128 GB 256 GB 512 GB 750 GB 1000 GB
Samsung 850 Pro 470 MB/s 520 MB/s 520 MB/s 520 MB/s
Samsung 850 EVO 520 MB/s 520 MB/s 520 MB/s 520 MB/s
Samsung 840 Pro 390 MB/s 520 MB/s 520 MB/s
Samsung 840 EVO 410 MB/s 520 MB/s 520 MB/s 520 MB/s 520 MB/s


Fundamental differences

The price difference is justified mainly in the memory type used and the associated (minimum) service life. In NAND flash memory of home users SSD, a distinction is made between MLC (Multi-Level Cell), TLC (triple-level cell) and their stacking in multiple layers in the form of 3D VNAND.


840 EVO Series

Samsung uses in its EVO series TLC flash memory. This Triple-Level-Cell-Flash (TLC) can store 3 bits per cell, which makes it compared to MLC memory (with only 2 bits per cell) more cost-effective. At the same time, however, TLC is always a little slower. To minimize these performance shortcomings, Samsung uses in the 840 EVO a three-level cache (Turbo write cache) back. As long as can be written to this cache (size 3-12GB, depending on the model), the 840 EVO is very fast and achieved a similar performance to the Samsung Pro Series. If this buffer is full, that presses heavily on performance. However, in everyday life, most files are likely to be rare several gigabytes in size, so the Turbo write cache can always catch everything.

Warranty and lifetime

Because the max. number of write cycles is limited per memory cell, the wear is higher with TLC flash memory in comparison to MLC flash memory. This can therefore be reflected in a somewhat shorter lifetime, because with each write access always all three bits will be erased and rewritten (even if only one bit changes). Samsung gives 3-year manufacturer’s warranty. According to Samsung, the 840 EVO reaches a daily writing performance of min. 40 GB over 3 years (= total 43 TB). Since rare 40 GB are written daily on the SSD in the home user area, experience has shown that a significantly longer service life than 3 years can be expected.

Samsung 840 EVO, 120 GB
Samsung 840 EVO, 250 GB
Samsung 840 EVO, 500 GB
Samsung 840 EVO, 750 GB
Samsung 840 EVO, 1000 GB


840 Pro Series

The former Samsung’s flagship relies on MLC flash memory and can store 2 bits per cell. Thus, the 840 Pro SSD offers, even with large files, consistent performance values and not without reason it still counts to the currently fastest SSDs. For applications such as office and gaming, no appreciable difference to the 840 EVO will be noted.

Warranty and lifetime

Samsung guarantees for the 840 Pro Series a write performance of 75 TB and gives 5-year manufacturer’s warranty. A total write performance of 75 TB is equivalent to the daily writing performance of 40 GB over 5 years.

Samsung 840 Pro, 128 GB
Samsung 840 Pro, 256 GB
Samsung 840 Pro, 512 GB


850 EVO Series

Since the end of 2014 the successor to the popular 840 EVO is now available. In the 120/250/500GB versions the new Samsung MGX controller is installed, the 1TB model uses the 3-core MEX controller of the 850 Pro. The MGX controller has only two instead of three cores, which are clocked at 400 MHz just like the cores of the MEX. Both controllers promise improved energy efficiency compared to 840 series.

As with the 850 Pro, Samsung uses in the 850 EVO vertical 3D NAND memory. But in contrast to the big brother favorable TLC memory cells are used instead of MLC memory cells. The TLC memory cells are laminated in 32 layers one above the other. The wear of TLC flash cells as compared to the MLC flash cells is slightly higher. However, the 3D VNAND design should significantly increase the lifetime and robustness of TLC memory cells.

Warranty and lifetime

The guaranteed write performance of the smaller models (120/250 GB) is 75 TB Written. Samsung even promises for the 850 EVO with 500GB and 1TB storage capacity a writing performance of 150 TB Written. But in contrast to the 850 Pro, Samsung gives only a 5-year manufacturer’s warrantyis for the EVO-series. Nevertheless the 850 EVO survives in the home user area the application duration of most computers.

Samsung 850 EVO, 120 GB
Samsung 850 EVO, 250 GB
Samsung 850 EVO, 500 GB
Samsung 850 EVO, 1000 GB


850 Pro Series

With the new 850 Pro Series Samsung offers the current king’s class in the area of home users SSD. The improvements mainly concern the storage and long-term performance. Up to now Samsung uses for the 840 Pro a normal MLC-flash memory. Now this was replaced with threedimensional, so- called 3D-VNAND (MLC), flash memory. Besides the MLC flash cells are stacking in multiple layers. These will be read by the new Samsung 3-core MEX Controller. The advantage of V NAND is in addition to a higher storage density especially the significantly longer lifetime.

Warranty and lifetime

According to Samsung, the individual cells tolerate a particularly large number of write cycles in 3D V-NAND. For the SSD of the Series 850 Pro the guaranteed write power is enclosed to 150 TB Written (TBW), which corresponds to a daily (!) writing performance of more than 40 GB over 10 years. So that in practice the 850 Pro survives the period of use of most pc’s or notebooks. Therefore, Samsung gives a self-confident 10 year warranty on the 850 Pro Series.

Samsung 850 Pro, 128 GB
Samsung 850 Pro, 256 GB
Samsung 850 Pro, 512 GB
Samsung 850 Pro, 1000 GB


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