by Corinne O'Brien

Kingston SDHC/SDXC UHS-I U3 Review

The Kingston SDHC/SDXC UHS-I U3 flash memory card comes in 16GB, 32GB, and 64GB storage capacities.  The UHS-I U3 flash memory card is designed for use in D-SLR or D-SLM cameras and 4K camcorders, advertising impressive 90MB/s read and 80MB/s write speeds to smoothly capture new high-resolution video output standards. 

The want and need for larger and faster memory cards comes as consumers and electronics vendors push the boundaries with higher resolution 2K or 4K video as well as higher burst rates on traditional cameras.  Supporting greater read and write speeds also help increase work flow efficiency; allowing users to quickly pull media off the flash cards for processing and archiving.

Not only can the Kingston SDHC/SDXC UHS-I U3 card be used to capture professional HD video, but also offers the versatility of Class 10 performance when used in a non-UHS-I capable devices, like high-performance D-SLR and D-SLM cameras.  The Kingston SDHC/SDXC UHS-I U3 is compliant with the SD Card Association and offers security features such as the built write-protect switch that prevents accidental data loss.

Kingston SDHC/SDXC UHS-I U3 Card is now available with a street price of $105, $59 and $39 for the 64GB, 32GB and 16GB cards respectively.  Each card includes a life-time warranty.  For our review Kingston supplied the 64GB model.

Kingston SDHC/SDXC UHS-I U3 Card Specifications

  • Capacities: 16GB, 32GB, 64GB
  • Voltage: Voltage range for communication: 3.3V
  • Operating Temperature -13 to 185°F (-25 to 85°C)
  • Non-operating Temperature: Storage Temperature -40 to 185°F (-40 to 85°C)
  • Dimensions (WxHxD) : 24mm x 32mm x 2.1mm
  • Type of NAND chip used: Samsung/Micron
  • Data transfer speeds: 80MB/s Write and 90MB/s Read speed UHS-I Speed Class 3 (U3)
  • Warranty: Lifetime
  • Free dedicated professional technical support

Design and Build

As with many of the Kingston SD cards, including the UHS-I U3, it features a unique design on the face of the memory card.  This memory card has a maroon brushed nickel decal, distinguishing it from the others in the Kingston brand.  Kingston has printed the brand, write speed, read speed and capacity on the face of the card, also included is the slide lock which will enable the prevention of data loss.

On the back side of the SDHC/SDXC UHS-I U3 card there are 9 gold pin connectors.  Additional material such as regulatory information and the products serial number are printed on the rear of the card.


In this review, we will include the following comparables with their respective advertised performance numbers:

Komputerbay 128GB SDXC 600X UHS-I (90MB/s Read, 60MB/s Write)
Samsung SDXC Pro Series (80MB/s Read, 40MB/s Write)
Lexar Professional 600x SDXC UHS-I (90MB/s Read, 45MB/s Write)

Using our Consumer Testing Platform, we measured transfer speeds from the 64GB Kingston SDHC/SDXC UHS-I U3 card using IOMeter. Sequential read speeds measured 89.6MB/s, while write activity hit 59MB/s. The read spec was right in line with what Kingston quoted, although the write speed came up short.  While slightly slower than the rated 80MB/s, 59MB/s did put it at the top of the pack. The Komputerbay 128GB SDXC card measured 81.3MB/s read, while write activity hit 58.3MB/s. It beat the Samsung SDXC Pro Series 64GB capacity quite handily, which hit sequential read speeds at 75.2MB/s, while write activity hit 38.1MB/s. The Lexar Professional 600x SDXC fared better than the Samsung, scoring an identical read speed of 81.3MB/s to the Komputerbay with a write speed of 44.3MB/s.

Switching to random large-block transfers, we measured 86.8MB/s read and 11.2MB/s write. In contrast the Komputerbay SDXC 128GB card measured 79.2MB/s read with a write speed of 10.3MB/s. The Samsung SDXC Pro Series posted a score of 67.5MB/s read and 7.0MB/s write. The Lexar Professional tallied in at 79.6 MB/s read and 10.8 MB/s write, just slightly better than Komputerbay card.


Kingston positions the SDHC/SDXC UHS-I U3 at media professionals that want to capture higher 2K and 4K video, with transfers speeds as high as 90MB/s read and 80MB/s write. While most high-performance SD cards have generally sold on their performance numbers alone, Kingston pushes this card specifically towards the professional content creation market, with capacities including 16GB, 32GB and 64GB.

In our testing environment the Kingston SDHC/SDXC UHS-I U3 proved to be the quickest SDXC card we've tested to date, although write speeds did measure slower than its claim of 80MB/s. In our consumer testing platform the SD card came in at 89.6MB/s for sequential reads and 59MB/s for sequential writes.


  • Class leading performance
  • Competitive pricing


  • Write performance below product specifications

Bottom Line

The Kingston SDHC/SDXC UHS-I U3 is a memory card designed for professional content creators who demand high performance coupled with an affordable price.

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