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HD Tune — Transfer rates
HD Tune lets us present transfer rates in a couple of different ways. Using the benchmark's "full test" setting gives us a good look at performance across the entire drive rather than extrapolating based on a handful of sample points. The full test gives us fodder for line graphs, which we've split up by drive maker. You can click the buttons below each line graph to see how the Samsung 840 EVO compares to its rivals.


The Samsung 840 EVO largely matches the sequential read speeds of rest the 840 family. Although the SanDisk Extreme II comes out on top, the 840 posse isn't far behind. Neither is the Crucial M500, for that matter.


The field is more spread out in HD Tune's sequential write speed test. Again, the 840 EVO hangs close to the 840 Series. This time, however, the 840 Pro has a solid lead over its entry-level siblings. The Crucial M500 isn't even close.

If you look at the line graphs, you'll notice that the 840 EVO's transfer rate is slightly faster at the very beginning of the test. Performance levels off pretty quickly, and I suspect TurboWrite may be responsible for that initial burst.

HD Tune runs on unpartitioned drives, with no file system in place, which might explain the write-rate spikes exhibited by some of the SSDs. For another take on sequential speed, we'll turn to CrystalDiskMark, which runs on partitioned drives. We used the benchmark's sequential test with the default 1GB transfer size and randomized data.

CrystalDiskMark produces higher sequential transfer rates overall, and the Samsung 840 EVO remains among the leaders. The default 1GB test size is small enough to fit inside the TurboWrite cache, which appears to be responsible for a massive performance improvement versus the previous generation. The 840 EVO more than doubles the sequential write speed of the old 840 Series.