Performance of 6 microSD/SD cards and 2 Card Readers

I wanted to examine the real read/write speeds of SD/microSD cards to see the deviation compared to the manufacturer values. Looks like things are even better! One thing I noticed is that the card reader used makes quite a big difference.   The miroSD and SD cards used for this test are:

  1. Samsung microSDHC Plus UHS-I 32GB (MB-MPBGC)
  2. Adata Premier microSDHC UHS-I Class10 32GB (AUSDH32GUICL10-R)
  3. SanDisk Ultra® microSDHC UHS-I 16GB (SDSDQUA-016G)
  4. Kingston microSDXC UHS-I 64GB (SDCA10 64GB)
  5. Apacer SD 256MB 60x (83.B256F.200)
  6. Adata SDHC Class6 8GB (G08GNMB9A0140)
  7. Transcend SDHC Class6 16GB (TS16GSDHC6)

SD Cards   The USB Card Readers used for this test are:

  1. Generic USB 2.0 Multi Card Reader (bought from eBay)
  2. Kingston MobileLite G4 (FCR-MLG4)

Card Readers The rated speed of the manufacturers for the cards are:

  1. Samsung 32GB: 48MB/s Read Speed
  2. Adata microSD 32GB: 30MB/s Read Speed and 10MB/s Write Speed
  3. Sandisk Ultra 16GB: 30MB/s Read Speed
  4. Kingston 64GB: 90MB/s Read Speed and 45MB/s Write Speed
  5. Apacer SD 256MB: 9MB/s Read Speed
  6. Adata SD 8GB: 6MB/s Write Speed
  7. Transcend 16GB: 16MB/s Read Speed and 6MB/s Write Speed

The tests were run with h2testw 1.4 using a 2GB file. The file was first written to each card by the program and then it was verified. That process uses write and read so it tests everything we want to test. The cards were all formatted using the FAT32 file system using the default Allocation Unit Size.   First we’ll have a look at the performance of the cards using the Generic USB 2.0 card reader in the chart below. image003 In the chart above we can see that the Generic USB card reader has a limit of around 18MB/s when reading. This isn’t a big limitation but it’s far from the usual transfer speeds we get from a USB 2.0 device, which is around 25-30MB/s. The cards on the other hand perform very good having higher write speeds than the manufacturer states. There is one exception though. The SanDisk Ultra performs a bit lower, but that could be from the Generic card reader. We’ll have a look at this at the next chart.   Next is the Kingston MobileLite G4 USB 3.0 card reader, plugged in a USB 2.0 port. This way we can see the difference between a good brand card reader and a no-name one.   image001 Here we can see, that the difference between a good and a generic card reader makes a big difference in transfer speeds. It looks like that the better cards are reaching the limit of the USB 2.0 port. All cards have a higher read and write speed and they also perform above the manufacturer rated speeds with the exception of the Apacer SD card. I do not blame this card. Its pretty old but performs like a Class 6 card!   Finally, we see the results when the Kingston card reader is plugged in a USB 3.0 port. This way we can also see the max capabilities of the cards since there is no speed limitation from USB 2.0 image003 As you can see, the difference in read speed is very big when the card supports high speeds. The Kingston 64GB microSD transforms to a different card completely when using a USB 3.0 port and card reader. Also, the Adata 32GB  microSD and the SandiskUltra 16GB have a lot higher transfer speeds than the manufacturer states, around 12MB/s, which is a lot! The same goes for the Kingston 64GB microSD writing speed. A whooping 22.6MB/s higher! On the other hand, the read speed is 10MB/s lower, but I don’t think it matters a lot since, 80MB/s is already very fast for a microSD card. The Samsung 32GB also has the same behavior. It has a higher write speed, but a bit lower read speed than the rated one.   The last test I run was with a Samsung NX300 mirror-less camera. I wanted to measure the speed of the SD card controller in the camera and see if it is worth it to get a fast SD card or not. I used the Kingston 64GB microSD which is the fastest of the lot. The results are the following.

  • NX300 Read Speed: 26.6MB/s
  • NX300 Write Speed: 23.1MB/s

So, it looks like the best suited card for the task is the Kingston 64GB but only because it has the higher Write Speed. So, if you want a card for this camera, get a card that writes at 25MB/s. No need to go higher.   At the end, we can see, that manufacturers deviate a bit from their rated speeds, stating either higher or lower speeds. The good thing is, when the deviate lower, there isn’t much of a difference, but when they deviate higher, there is a big difference and of course, that is good for us consumers! Is it worth it to get an expensive microSD or SD card that is fast or go with a plain Class 6 or Class 10? For example a simple Class 10 Kingston 64GB costs 32€ and the Kingston 64GB I reviewed costs 48€. I’d say go for the fast one. Our current generation of gadgets might not support so high speeds, but in the future they might will. And 64GB will still be enough by that time.

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