With their 1 Terabyte Drive we've already had on new Samsung 840 Evo SSD for review and we were quite surprised. Now it's time we have a closer look at the 120 Gigabyte version of the drive. Usually 120 Gigabyte Drives don't offer the same performance level bigger drives offer, which is why we're really curious to see if Samsung has found a way around this issue.


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Specifications / Delivery

Model	840 Evo 120 Gigabyte	840 Evo 250 Gigabyte	840 Evo 500 Gigabyte	840 Evo 750 Gigabyte	840 Evo 1000 Gigabyte
Capacity	120 GB	250 GB	500 GB	750 GB	512 GB
Form Factor	2.5'', 7 mm	2.5'', 7 mm	2.5'', 7 mm	2.5'', 7 mm	2.5'', 9.3 7 mm
Memory	TLC NAND 19nm ~1'200 P/E-cycles	TLC NAND 19nm ~1'200 P/E-cycles	TLC NAND 19nm ~1'200 P/E-cycles	TLC NAND 19nm ~1'200 P/E-cycles	TLC NAND 19nm ~1'200 P/E-cycles
Model	Samsung K90KGY8S7M-CCK0	Samsung K90KGY8S7M-CCK0	Samsung K90KGY8S7M-CCK0	Samsung K90KGY8S7M-CCK0	Samsung K90KGY8S7M-CCK0
Throughput	540 MB/s sequential read 410 MB/s sequential write 94'000 IOPS 4K random read 35'000 IOPS 4K random write	540 MB/s sequential read 520 MB/s sequential write 97'000 IOPS 4K random read 66 '000 IOPS 4K random write	540 MB/s sequential read 520 MB/s sequential write 98'000 IOPS 4K random read 90 '000 IOPS 4K random write	540 MB/s sequential read 520 MB/s sequential write 98'000 IOPS 4K random read 90 '000 IOPS 4K random write	540 MB/s sequential read 520 MB/s sequential write 98'000 IOPS 4K random read 90 '000 IOPS 4K random write
Accesstime (read)	< 0.1 ms	< 0.1 ms	< 0.1 ms	< 0.1 ms	< 0.1 ms
Acoustics	no noise	no noise	no noise	no noise	no noise
Warranty	3 Years	3 Years	3 Years	3 Years	3 Years
Price

One of the biggest issues with the Samsung 840 (non Pro) was its sequential write performance of 130 Megabyte per second. Since at this point Samsung just wasn't competitive at all, they really had to do something about this to boost this value into a region where it can compete with for example Crucials M500 SSD. Apart from that Samsung also boosted IOPS performance, when you compare the 840 Evo with the older 840 drives.

At this point you should really ask yourself what kind of sorcery is going on behind the scenes that Samsung was able to triple sequential write performance from one generation to another. The key to success actually has a name: TurboWrite. That's what the new proprietary technology has been called and basically it is an algorithm, which has been implemented into the firmware of the 840 Evo's new MEX controller. TruboWrite can use a small portion of the DRAM chip, which sits next to the controller on the SSD's PCB and emulate SLC NAND flash. As soon as there are data transfers this emulated SLC cache acts as a high performance buffer. In other words, Samsung brought the concept of DRAM caching into the SSD controller, which massively boosts sequential write performance, that used to be the achilles heel of the 840 Evo's predecessor.

Next to the improvements on the controller Samsung has also been working on their Magician Software. Overall it is very well structured and even unexperienced users will have no issues at all configuring the drive the most suitable way.
Last but not least there is the actual price of these drives. In case of the large 1 TB drive you get a price per GB of 0.48 EUR, which make big SSD's finally affordable. A closer look at the 120 Gigabyte drive reveals, that the price per Gigabyte is at 0.72 EUR, which is still very good but apparently not as attractive as with the 1 TB drive.

Page 1 - Introduction	Page 6 - Random write KByte/s
Page 2 - Impressions	Page 7 - Random read KByte/s
Page 3 - How do we test?	Page 8 - Random write IOPS
Page 4 - Sequential write KByte/s	Page 9 - Random read IOPS
Page 5 - Sequential read KByte/s	Page 10 - Conclusion