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SanDisk Extreme microSDXC UHS-I Memory Card Review
Date: Jul 26, 2013
Author: Marco Chiappetta
Introdcutions and Specifications

A couple of weeks back, SanDisk launched a new line of Class 10 UHS-I microSDHC / microSDXC cards targeted at performance conscious consumers. When describing the cards, SanDisk’s director of retail product marketing Susan Park said, “The SanDisk Extreme microSDXC card allows users to do more with their devices…Our high-performance and high-capacity microSD cards enable consumers to take advantage of the high-quality HD video and imaging capabilities in the latest 4G smartphones, tablets and action cameras."

With up to 80MB/s read and 50MB/s write speeds, the new SanDisk Extreme microSDXC cards should easily be able to handle the needs of users taking photos and videos on today’s mobile devices, be it a smartphone or tablet or even a high-end camera. And with capacities up to 64GB, the cards offer plenty of storage space too.

We’ve had the top of the line 64GB SanDisk Extreme microSDXC card in house for a couple of weeks now and it’s worked flawlessly in a number of devices, ranging from a new Olympus PEN camera to an as-yet-released portable gaming device. Compatibility is one thing, but we figured many of you would be interested to see if SanDisk’s performance claims were realistic too, so we ran a couple of benchmarks on the thing to see just what it could do. Before we get to the numbers though, here are some pictures and specifications...

SanDisk Extreme microSDXC Cards
Specifications & Features

  • Form factor: microSDHC (16 GB and 32 GB), microSDXC (64 GB)
  • Available capacities: 16 GB, 32 GB, 64 GB (1GB=1,000,000,000 bytes. Actual user storage less.)
  • Performance/speed: Up to 80/50MB/s Card only. Up to 80MB/sec read; up to 50MB/s write (32 &64GB). Up to 80MB/s read; up to 30MB/s write (16 GB). Based on internal testing; performance may be lower depending upon host device. 1 megabyte (MB) = 1 million bytes. read/write speed (32 GB & 64 GB); Up to 80/30MB/s Card only. Up to 80MB/sec read; up to 50MB/s write (32 & 64GB). Up to 80MB/s read; up to 30MB/s write (16 GB). Based on internal testing; performance may be lower depending upon host device. 1 megabyte (MB) = 1 million bytes. read/write speed (16 GB)
  • Card dimensions: 0.59 in x.43in x.04in (15 mm x 11 mm x 1.0 mm)
  • Operating temperature: -13ºF to 185ºF (-25ºC to 85 ºC)
  • Storage temperature: -40ºF to 185ºF (-40ºC to 85ºC)
  • Compatibility: Compatible with all microSDHC, microSDXC, microSDHC UHS-I, and microSDXC UHS-I supporting host devices (Not all devices support microSDXC memory card formats.)
  • RescuePro Deluxe data recovery software downloadable offer. (Registration required; terms and conditions apply.)
  • Support: Lifetime limited warranty (30 year warranty in Germany, Canada, and regions not recognizing lifetime limited warranty.)

Save for its red and gold color scheme, the SanDisk Extreme card looks just like any other microSDXC device (obviously). Included with the cards is a simple adapter and a plastic case (not pictured). Other than that, there’s not much else to report in terms of the product’s aesthetics or bundle, though SanDisk does also offer a downloadable copy of RescuePro Deluxe data recovery software should you register the product and the company claims the cards are waterproof, X-ray proof, temperature proof, and shock proof as well.

Transfer Speeds and Performance

To evaluate the performance of SanDisk’s Extreme microSDXC card, we plugged into a USB 3.0 FCR-HS3 card reader, connected to our Core i7-3960X / X79 Express-based test system, running Windows 8 Pro x64. In addition to monitoring performance during simple file transfers, we also ran a trio of benchmarks to see how the card handled different data types and transfer sizes. First up, ATTO’s Disk Benchmark.

As you can see in the image above, the SanDisk’s Extreme microSDXC card doesn’t hit its stride until the 64K mark, but when it does, performance actually exceeds SanDisk’s specified 80MB/s (read) and 50MB/s write speeds. According to ATTO, the SanDisk Extreme microSDXC card peaks at about 94.5MB/s and 61.7MB/s, for reads and writes, respectively.

CrystalDiskMark tells essentially the same story as ATTO. In this benchmarks, SanDisk’s Extreme microSDXC card tops out with 92.56MB/s and 61.45MB/s sequential reads and writes. Performance is also good in the 512K test, though the card struggles with smaller 4K transfers.

Finally we ran Anvil’s Storage Utilities SSD benchmark. This test is complete overkill for a microSDXC card, but if you want to full scoop on the SanDisk Extreme microSDXC card’s performance, there it is. As you can see, in the Sequential 4MB tests, the card has no trouble exceeding the speeds listed in card’s specifications.

We should also note that we monitored transfer speeds in a number of everyday usage scenarios, copying images and videos to and from the card, and it regularly exceeded SanDisk’s specifications. Read speeds of 88MB/s were common, with 58MB/s writes.

Our Summary and Conclusion
Alright, at this point you’ve seen that SanDisk’s performance claims for their Extreme series microSDXC cards are the real deal. In both real-world situations and in synthetic benchmarks, the 64GB SanDisk Extreme microSDXC card we tested had no problem exceeding the speeds presented in SanDisk’s specifications, usually by about 10% - 15%. Keep in mind, however, you’ll need a device or card reader capable of the higher transfer speeds. And old USB 1.0 reader ain’t gonna cut it.

They’re not exactly cheap, but the SanDisk’s Extreme microSDXC cards are worth the extra scratch if you’re in need of a high-performance memory card. As of today, you can find the SanDisk Extreme micoSDHC / microSDXC cards on-line at the following price points:

At this prices, you can find similar capacity cards for roughly half the amount, but they won’t perform nearly as well. The Class 10 and UHS-I specifications call for a minimum transfer speed of only 10MB/s. With over 80MB/s and 50MB/s reads and writes, respectively, these SanDisk Extreme cards obviously exceed the minimum spec. Cheaper cards do as well—it’s common to find 64GB cards that offer 50MB/s reads and 10MB/s writes—but they don’t come close to what the SanDisk Extreme cards can do.

  • Great Performance
  • Lifetime Warranty
  • Kinda Pricey

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