SanDisk Extreme UHS-I microSDXC Card SDSDQX Review


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UHS-I microSDXC Final Thoughts

There’s a lot of confusion surrounding microSD card speeds, and it stems from nomenclature that seems intended to confuse. The SD Association defines standard speed classes for secure digital cards, which replace speed-x ratings:

Class 2 (C2) =  2 MB/s (replaces 16x rating, 13x actual)
Class 4 (C4) = 4 MB/s (replaces 32x rating, 27x actual)
Class 6 (C6) = 6 MB/s (replaces 48x rating, 40x actual)
Class 10 (C10) = 10 MB/s (replaces 100x rating, 67x actual)
UHS Speed Grade 1 (U1) = 10 MB/s

Then there’s the Ultra High Speed rating, which gets the same naming symbol but is divided into several sub-speed:

Ultra High Speed (UHS-I) = 50 MB/s (100 MHz)
Ultra High Speed (UHS-I / UHS104) = 104 MB/s (208 MHz)

As seen in this review, some UHS-I speed-graded memory cards do not perform to 50 MB/s minimum Ultra High Speed specifications yet maintain the 10 MB/s UHS Speed Grade 1 rating. This indicates that some manufacturers may have also been confused by the rating system, which makes it critically important to check reviews.


SanDisk Extreme Conclusion

RATING DISCLAIMER: Although the rating and final score mentioned in this conclusion are made to be as objective as possible, be advised that every author perceives these factors differently. While we each do our best to ensure that all aspects of the product are considered, there are often times unforeseen market conditions and manufacturer revisions that occur after publication which could render our rating obsolete. Please do not base any purchase solely on this conclusion, as it represents our rating specifically for the product tested which may differ from future versions. Benchmark Reviews begins our conclusion with a short summary for each of the areas that we rate.

Our first rating is Performance, which compares how effective the SanDisk Extreme microSDXC memory card performs in read and write operations against competing SD-based solutions. In our tests we compared the SanDisk Extreme microSDXC card to another so-called UHS-I product, but only the SanDisk card could reach and surpass the 50 MB/s minimum write specification. ATTO Disk Benchmark produced a peak write speed of 62 MB/s, while AIDA64 and AS-SSD generated 57 MB/s write speeds.

There really isn’t very much that can be done to dress-up a dime-size product. SanDisk has matched their Extreme-series SD cards to the red and gold company color theme, which immediately improves upon the dull white text on black memory card seen everywhere else.

microSD cards are delicate, wafer-thin products that can snap if given too much pressure or melt if the card becomes too hot. Call it a side effect of the ‘micro’ design, but these are not durable components. However, SanDisk asserts their cards to be waterproof, X-ray proof, temperature proof, and shockproof. If any SanDisk Extreme microSD storage product does happen to fail during its limited-lifetime warranty period, end-users may contact SanDisk at their toll-free telephone number (866-726-3475) for technical support or customer service questions.

In terms of functionality, the SanDisk Extreme microSDXC UHS-I card does exactly what it’s been designed to do – and it does it very, very fast. The bundled SD card adapter allows users to retro-fit this product into older devices that use Secure Digital storage, instead of microSD cards. The adapter also enables easy transfer of files to computer systems using older SD card media ports.

As of July 2013, the 64GB SanDisk Extreme microSDXC memory UHS-I memory card was available online for $99.99 (Amazon | Newegg). With regard to value, this price matches every other product with the same specifications and capacity. However, SanDisk offers a limited lifetime product warranty in addition to toll-free product support, so not all products are truly the same.

Summary: unlike other SD cards we’ve tested, the SanDisk Extreme microSDXC memory UHS-I memory card actually performed to beyond specification and produced write transfers at up to 62 MB/s. 64GB is a lot of room for digital photos, but if you’re recording 1080p video at 30 FPS or better that capacity will fill quite fast. With phones, tablets, and other portable devices capable of HD video recording onto microSD cards, it makes sense to purchase the fastest and largest capacity available. I highly recommend the 64GB SanDisk Extreme microSDXC card for high definition video recordings and large-resolution digital photography.

Pros:Benchmark Reviews Golden Tachometer Award Logo (Small)

+ 64GB microSDXC extended capacity
+ Very fast 62 MB/s write speeds
+ Ideal for high frame rate HD video recording
+ Includes SD card adapter for backwards compatibility
+ Limited lifetime product warranty
+ Exceptional 97 MB/s read speed
+ True UHS Speed Class 1 (U1) storage product
+ Waterproof, X-ray proof, temperature proof, and shockproof


– No notable concerns


  • Performance: 9.00
  • Appearance: 9.25
  • Construction: 9.25
  • Functionality: 9.50
  • Value: 8.00

Final Score: 9.0 out of 10.

Excellence Achievement: Benchmark Reviews Golden Tachometer Award.

COMMENT QUESTION: Does speed make a difference for your microSD memory card needs?



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