Roundup: USB 3.0 External Drives with 750 GB Storage Capacity

We have already learned that not all USB 3.0 flash drives are equally good. But is the same true about the external USB 3.0 hard drives or their performance difference will fall within the measuring error margin? Let’s check out seven products from Seagate, Silicon Power, Transcend and Western Digital to answer this question.

by Dmitry Vasiliev
11/10/2011 | 09:57 AM

To compare external HDDs with the most popular interface, we've taken seven products from four brands. All of them have the same storage capacity of 750 gigabytes (traditionally for HDDs, these are decimal gigabytes, so the real capacity of each model is somewhat lower than 700 “normal” gigabytes).


Two of the products to be tested come from the well-known makers of HDDs, Seagate and Western Digital. Two more are provided by Transcend and the remaining three, by Silicon Power.

Testing Participants

We will present the products to you in alphabetic order.

Seagate FreeAgent GoFlex STAA750201


We used this external HDD in our review of USB 3.0 flash drives for the sake of comparison. It's got a typical exterior design for its product class: a flat box with rounded-off edges. The box is black; the activity indicator is white.

The key distinguishing feature of Seagate's GoFlex series is that you can replace the interface by purchasing adapters for FireWire 800 or eSATA.


Silicon Power Diamond D10


This small box with a shimmering blue pattern on its top panel looks cute. The USB connector is located on a longer side panel rather than on a shorter one.


The HDD comes with a pouch which is made of artificial leather that feels nice but doesn't smell pleasantly. The lining of the pouch is some soft fabric.

By the way, you can't connect a USB cable to this HDD without taking the latter out of the pouch.

Silicon Power Stream S10


The shape and color of the junior model in the Stream series do not match each other well. If this design is supposed to convey the speed-inspired style of Italian sports cars, red would be much more adequate than this canary-green.

Otherwise, this model is similar to the Diamond D10. It's got the same packaging and accessories and its USB 3.0 connector is located on a longer side panel, too.


There are some differences, though. The pouch is designed as a book cover. It’s a cardboard frame wrapped into a piece of fabric with stitching the color of the HDD itself. The lining of the pouch is the same soft fabric as that of the Diamond D10's pouch. The two halves of the cover are joined with elastic straps that leave a lot of free space at the sides, making it possible to connect a USB cable to the HDD without taking the latter out of the pouch.

Silicon Power Stream S20


The Stream S20 is in fact identical to the above-discussed Stream S10 in its exterior design and accessories. The shape and dimensions of the case are somewhat different, but the overall style is unmistakably the same. Silicon Power draws inspiration from sports cars, but the result is still rather poor.


The Stream S20 comes with the same accessories as the Stream S10 except that it lacks a software disc.

Transcend StoreJet 25D3


This HDD is a plain black box with a gold-painted product name and manufacturer logo. Transcend claims that this model's case is shock-resistant thanks to a shock-absorbing pad the HDD proper is wrapped into.

The downside of this model is that it is recommended to be used with an additional USB power cable. It is not handy to connect two cables instead of just one. Although we didn't observe any problems when this HDD was connected with one USB cable only (and there were no difference in performance, either), we followed the manufacturer's recommendation and used the additional power cable during our tests.

This HDD comes with a soft pouch made of artificial suede.

Transcend StoreJet 25M3


The second Transcend product in this review is far more attractive thanks to its matte rubber pouch with green edging. It's not so easy to pull the pouch off the HDD, but we don't think you’ll need to do that anyway.

The manufacturer claims that this HDD complies with USA military standards in terms of protection. Every sample has passed a drop test.

The StoreJet 25M3 has an automatic backup button that can be used after installing the Transcend Elite tool which also supports encryption.

This model has the same downside as the above-discussed StoreJet 25D3. It needs a second USB cable for additional power supply.

If we were to choose the best external HDD in terms of exterior design and protection, the Transcend StoreJet 25M3 would be our favorite, but we are yet to see how fast it is.

Western Digital My Passport Essential SE


This model is smaller than the other products in this review. Its width and height are comparable to those of the other HDDs but its length is much smaller. Despite the compact dimensions, it is surprisingly heavy.

Rather surprisingly too, Western Digital talks about a threefold advantage of USB 3.0 over 2.0 in terms of data-transfer rate whereas the other manufacturers claim that the newer version is 10 times as fast as the older one. Well, Western Digital is quite right here because, even though the theoretical bandwidth of the two USB versions indeed differs by a factor of ten, today’s HDDs just cannot utilize the USB 3.0 bandwidth to the full extent.

When we connected this HDD to our testbed, we found that one driver was missing. The WD SES driver (its distribution file can be found on the HDD itself) serves to implement password-based protection and some other features and its presence does not affect the product’s speed. However, it is rather annoying to get the missing driver message, especially as you can only get rid of it by installing the SES driver even if you don’t really need it (and you have to do so on each computer you regularly connect your Essential SE to).

The Western Digital drive comes with the fewest accessories of all the products in this review. There is nothing inside its package save for the HDD and a USB 3.0 cable.

Testbed and Methods

Our testbed was configured as follows:

We installed the latest drivers from the manufacturers of our components. The tested disks were not reformatted; we used the file system and cluster size chosen by their makers.

Each HDD was connected to the mainboard’s back-panel USB 3.0 ports based on an ASMedia ASM1042 controller.

We used the following benchmarking tools:

There were three FC-Test patterns corresponding to three typical usage scenarios:

We also used CrystalDiskMark for you to be able to compare your results with ours if you want. We ran each test of that benchmark five times using 1000 megabytes of test data.


Let’s start out with CrystalDiskMark.

Seagate FreeAgent GoFlex

The Seagate drive’s results will serve as the baseline since we know them from our previous review.

Silicon Power Diamond D10

CrystalDiskMark suggests that the Silicon Power Diamond D10 is faster than the Seagate in sequential reading but slower in writing 512KB data blocks as well as in reading small and medium-sized files.

Silicon Power Stream S10

Being inferior to the two previous HDDs in sequential reading and writing, the Silicon Power Stream S10 is considerably faster in writing small and medium-sized files and delivers a comparable performance when reading such files.

Silicon Power Stream S20

Compared to its series mate, the Silicon Power Stream S20 is somewhat better in sequential reading and writing and faster in writing small and medium-sized files. It is slower than its cousin in reading those files, though.

Transcend StoreJet 25D3

Transcend’s first product StoreJet 25D3 is ahead of Silicon Power's Stream series but slower than the Diamond D10 and Seagate FreeAgent GoFlex in terms of sequential reading and writing. It is comparable to its opponents in reading small and medium-sized files but too slow when writing such files.

Transcend StoreJet 25M3

Transcend's second HDD, StoreJet 25M3, is almost the same as the StoreJet 25D3 in performance.

Western Digital My Passport Essential SE

Western Digital’s My Passport Essential SE has the lowest results in the sequential read and write tests but it is only second to the Silicon Power Stream S20 in the other write modes. Its random read results are average.

Now we can proceed to our File Copy test which is closer to real-life applications (you don't have files which are all exactly 512 or 4 kilobytes large as in CrystalDiskMark, do you?).

The next diagram shows the speed of reading:

When the HDDs read one large file, their results are close to the CrystalDiskMark ones: the Seagate FreeAgent GoFlex and Silicon Power Diamond D10 are beyond competition whereas the Western Digital falls behind its opponents.

The HDDs' performance with the other file-sets differs from what we've seen in CrystalDiskMark due to the different size of the processed files (a “medium-sized” file is 512 kilobytes in CrystalDiskMark but about 4 megabytes in FC-Test; the difference is even larger with “small-sized” files).

Most of the HDDs go neck and neck in the MP3 pattern but the Silicon Power Diamond D10 is ahead while the Western Digital lags behind.

When reading small files, the two Transcend drives are superior, closely followed by the Silicon Power Diamond D10 which has been good in every other read mode. Next go the other two drives from Silicon Power. The Western Digital is slow again. The slowest of the other drives is seven times as fast as the Western Digital, so the latter is a complete failure in this read test.

We’ve got a more complicated picture at writing.

When there is only one large file to write, the Seagate and the Silicon Power Diamond D10 again prove that they can do sequential reading and writing very efficiently. Third place goes rather surprisingly to the Western Digital which was the slowest in the sequential writing test from CrystalDiskMark. The Silicon Power Stream S20 and S10 are in the middle of the results table whereas the two Transcend drives aren’t very quick processing the 900MB file.

The standings change when we switch to the MP3 file-set. The Silicon Power Diamond D10 is ahead, followed by the Western Digital and Silicon Power Stream S20. Next goes the Seagate FreeAgent GoFlex, which is considerably slower than the leaders. Then there is the Silicon Power Stream S10 whereas the Transcend drives are as slow as in the ISO pattern.

Western Digital’s drive is best when writing the numerous small files of the Install pattern (but we must remind you that this drive is also awfully slow when reading the same pattern). The next three positions are occupied by the Silicon Power products, the Steam S20 being ahead of the Diamond D10 and Stream S10. Next goes the Seagate FreeAgent GoFlex while the Transcend duo is expectedly slow.

We must confess we were quite astonished at the results of the writing tests, especially the ISO pattern. Writing a single 900MB file should be close to CrystalDiskMark's sequential write, but many of the tested drives perform differently in these two tests. In fact, there are only three models out of seven that have the same performance in FC-Test’s ISO pattern as in CrystalDiskMark. However, we are sure there is no error in the benchmarking tools or patterns as we retested the slower drives and have adequate results from the faster ones.


The outcome of our tests is rather surprising: the Silicon Power Diamond D10, the most affordable model in this review, seems to be the overall winner. It features the highest speed of reading medium-sized and large files and isn't much slower than the leaders in reading small files. Its writing performance is impressive as well: second place with large files and first place with medium-sized files. It is only small files that the Diamond D10 can't write fast. None of the other products we've tested today can boast such versatility. The low weight, nice looks and affordable price are the additional factors in favor of this model.

The two Transcend drives were downright poor when writing files (the StoreJet 25M3 was somewhat faster in every test, but that doesn't make any serious difference) while the Western Digital was poor at reading. The latter's record-breaking performance in writing small files is negated by its awful speed of reading with the same files. The Silicon Power Stream S10 is but slightly better than the Transcend duo at writing but inferior to them at reading. It is at reading, especially with small and medium-sized files, that the Transcend drives deliver their best performance.

The Seagate FreeAgent GoFlex and Silicon Power Stream S20 can be viewed as average products that don’t have serious flaws in performance. The Seagate is somewhat better at reading large and medium-sized files and is far ahead when writing large files. The Stream S20, on its part, is preferable for writing small and medium-sized files as well as for reading small ones. Still, if we don't focus on one parameter but take them all together, none of these two models can match our overall winner Silicon Power Diamond D10.