This Sandisk ‘class-4′ micro-SDHC card is faster than a PNY ‘class-10′, December 2, 2011

By 

NLee the Engineer (Nashua, NH) –

  

  

I purchased a SanDisk 32 GB microSDHC Flash Memory Card SDSDQM-032G nearly two months ago, for use in my VIZIO 8-Inch Tablet VTAB1008. At the same time, I also purchased a higher-priced PNY 32 GB microSDHC Card (P-SDU32G10-EFS2) which is supposed to be a ‘class-10′. My benchmark results, however, show that the Sandisk class-4 card is actually faster – most of the time.

I used two sets of benchmark programs. One is called ‘Flash Memory Toolkit v2.0′, which measures the random read/write speed of files between 1MB and 15MB. The other one is called ‘H2testw v1.4′, which measures the sequential read/write speed using 1GB files. Here are my results: (see my uploaded charts in ‘Customer Images’ section for details)

- For smaller files (1-5MB), the Sandisk class-4 card gives an amazing write speed of 15-17MB/s, while the PNY ‘class-10′ card can only get 1-6MB/s

- For larger files (10-15MB), the Sandisk and PNY cards are about equal at around 8MB/s for write

- For huge files (1GB), the PNY did better at 9.5MB/S, while the Sandisk dropped to 5.5MB/s

- The read speeds of both cards are equally high at around 18MB/S (this number may be limited by the maximum speed of my card reader used)

What the above shows is that: When used in a typical digital camera (with file size 3-5MB), this Sandisk ‘class-4′ card is at least twice as fast as the PNY so-called ‘class-10′ card. But when used in a HD video camera (sequential writing of huge file), then the PNY card should perform better.

For a card to be marketed as a ‘class-10′, it must maintain a MINIMUM write speed of 10MB/s. So by this definition, the PNY card does not qualify since it cannot even achieve a MAXIMUM write speed of 10MB/s. This Sandisk card, on the other hand, exceeds the requirement of ‘class-4′ by a huge margin.

Sandisk seems to be the only flash memeory manufacturer that still gives honest, conservative speed class ratings. Any other manufacturers would have labeled this card a ‘class-6′ or even higher. As a matter of principle, I rather give my money to a company that promises less but delivers more, instead of to others that do the opposite. At the present cost of about 1 buck per GB, this is an unbeatable deal!

[Aside]
The capacity of this card, as reported by my computer, is only 29.7GB. Note that this is actually normal, because compter people define one ‘Giga’ as ’2 to the power 30′, which is 7.4% greater than 1 billion. So 29.7GB comes to just about 32 billion bytes, which is ’32GB’ according to marketing people.

[Update Dec 3, 2011]
I re-tested the two cards above, using the CrystalDiskMark v3.01. The results are consistent with my previous finding. See my newly uploaded charts in ‘Customer Images’ for details.

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No Problems, Works as Advertised, and Came With a MicroSD Card Adapter!, March 8, 2012

So I read some of the reviews about this microSD card and I wanted to chip in my experiences.

I purchased mine from Amazon.com via the vendor “MemoryMogul.” It arrived at my porch in a small envelope package and did not have any of the bulk packaging that one would find from a retail store. Inside this envelope was just a small plastic case holding the microSDHC card as well as a SanDisk microSD card adapter. This was surprising to me since it wasn’t advertised that this microSD card would come with an adapter. I guess that’s good in my case since I was going to purchase a separate adapter. The package did not come with an instruction manual, or any SanDisk packaging for that matter. [Please see the customer image I uploaded]

Apart from the unexpected package and its contents, everything about the microSD card works as advertised:
1. My Macbook and Dell laptops both recognized that 31.90 GB of space are available to use in my card. Some people have reported that they received cards with less available space.
2. Also relating to people’s complaints, some have said that they cannot write more than 10 GB of data onto their cards. I am happy to report that I can in fact write more than 10 GB of data to my card (right now I have about 17 GB of music and JPEG files loaded onto my card).
3. Still relating to peoples’ reported issues, my card has a read/write speed of 4.0 MB/s or higher, as it should since it’s a class 4 microSD card. Some have reported that the read/write speed is less than that. To put it to the test, I did many benchmark tests and compared it to other SD cards I have. If you are interested, I included them at the bottom of this review.

All in all, I am satisfied with my purchase. For $28 USD, this 32 GB class 4 microSDHC card is worth every penny. I will be using this product with my SanDisk SDMX22-004G-A57P Sansa Clip Zip 4 GB, Purple portable media player as an expandable memory option. Everything about the microSDHC card itself works as advertised according to the benchmark tests as well as practical file transfers. The included microSD card adapter was also a nice surprise to me and I no longer need to purchase a separate adapter.

________________________________________________________________________

And now for the boring stuff. You may skip this if you don’t care about the benchmark tests and comparisons.

To be honest, I don’t completely understand the results of the software benchmark tests, so if you can interpret them, more power to you. Because of this, I decided to do a bunch of real-world file transfers (copying) to test the write speeds of the [micro]SD cards. I chose various batch sizes for my tests to see if the size affected the cards’ write speeds.

That being said, all tests were done using the same SD card reader, microSD card adapter, music files, source for files, and up-to-date software:
Targus USB 2.0 SD card reader
SanDisk MicroSD card adapter
Macbook 5.1 running Mac OS X 10.6.8 (for file copy, AJA, and Xbench tests)
Files were copied/transferred from an Other World Computing On-The-Go Pro portable external hard drive via USB 2.0 (500 GB Seagate 7200.4 RPM Momentus hard drive)
Dell Vostro 1400 running Windows XP Home Edition SP3 with the latest updates installed (for ATTO, CrystalDiskMark, and Flash Memory Toolkit [free] tests)

I’m not sure if it matters or not, but while doing these tests, I left the computer alone so that no other computer processes would interrupt the tests.

SanDisk 32 GB Class 4 MicroSDHC, brand new
Mac OS X 10.6.8
Music File Copy Tests:
10 MP3 files, 109.1 MB total, 26s = 4.20 MB/s
15 MP3 files, 167 MB total, 41s = 4.07 MB/s
15 MP3 files, 164 MB total, 40s = 4.10 MB/s
10 Apple Lossless files, 299.5 MB total, 71s = 4.22 MB/s
10 Apple Lossless files, 308.6 MB total, 73s = 4.23 MB/s
12 FLAC files, 375.3 MB total, 87s = 4.31 MB/s
14 FLAC files, 456.1 MB total, 105s = 4.34 MB/s
14 FLAC files, 543.4 MB total, 125s = 4.35 MB/s
47 FLAC + 15 MP3 + 6 JPEG files, 1.46 GB total, 342s = 4.37 MB/s
64 FLAC + 12 MP3 + 6 JPEG files, 2.12 GB total, 498s = 4.26 MB/s
129 FLAC + 10 JPEG files, 3.24 GB total, 757s = 4.38 MB/s

AJA Tests:
128 MB 720×486 8-bit video: Write 4.0 MB/s Read 18.3 MB/s
128 MB 1280×720 10-bit video: Write 3.8 MB/s Read 18.4 MB/s

Xbench Disk Tests:
Sequential:
Uncached Write 4.30 MB/sec [4K blocks]
Uncached Write 4.04 MB/sec [256K blocks]
Uncached Read 3.63 MB/sec [4K blocks]
Uncached Read 19.48 MB/sec [256K blocks]
Random:
Uncached Write 0.93 MB/sec [4K blocks]
Uncached Write 0.56 MB/sec [256K blocks]
Uncached Read 2.80…

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