Back in march kingston announced some new UHS-I U3 microSD cards. These cards are new Gold Series microSD cards and are our first look at U3 class cards on the UHS-I bus.

Our sample

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Our sample is a retail packaged 64Gb card. Kingston has opted for a retail friendly blister pack with both specifications and the card clearly visible in the package. a U3 rating means a minimum of 30MB/s sustained sequential writes and a promise of up to 45MB/s is a welcome addition alongside the 90MB/s rated read speeds. An adapter for full size SD is included in the package as well. Finally the card is covered by a lifetime warranty.

A UHS Rehash

The UHS bus is available in a few different varieties. Although UHS-III was recently announced by the SD association we’re still seeing UHS-I devices as the most common with the SD835 in this years flagship devices still utilizing it as their highest speed bus. Hopefully this changes in the future.


As usual for microSD devices all benchmarks were run using a ThinkPad S1 yoga. We use Crystal disk mark 5.1.2 set to a 1Gb test size. testing was moved from the internal UHS-I limited reader to a UHS-II USB 3 card reader(the reader used was a Lexar UR2 reader). With that preface out of the way lets look at how things turned out.

Sequential writes are what the real prize on the Kingston Gold microSD. The U3 rating the card is rated for requires a minimum of a 30Mb/s sequential write speed and the card delivers, albeit without much wiggle room. Read speeds are a healthy 90Mb/s which is excellent however and approaches what UHS-I is capable of.

Although not part of our normal testing I was concerned when the card didn’t reach it’s rated 45MB/s write speed. To this end I decided to follow up CrystalDiskMark with ATTO. I ran ATTO under the same conditions we use for SSD testing ATTO. This produced writes peaking at 53MB/s for data sizes larger than CrystalDiskMark uses.

A note on filesystems

  Fat32 ExFat NTFS EXT3 EXT4 HFS+
Maximum File Size 4Gb 16 EiB 16 EiB 16 GiB to 2 TiB 16 GiB to 16 TiB 8EiB
Maximum Volume Size 512 MiB to 8 TiB 64 ZiB 16 EiB 2 TiB to 32 TiB 1 EiB 8 EiB
Name length limit 255 characters 255 characters 255 chars 255 bytes 255 bytes 255 UTF-16 characters
Windows Yes 7 and higher natively, XP and vista via patch Yes Partial Partial Partial
Linux Yes FUSE based due to liscensing Yes with ntfs-3g Yes Yes Partial
OSx Yes 10.6.6 and above Yes with ntfs-3g Partial Partial Yes
Android Yes Yes(5.0 and higher tested on htc m8/10) Yes(5.0 and higher tested on htc m8/10) Yes Yes Unknown

Normally I would skip the file system chart for microSD cards. However with Kingston mentioning both exFAT and FAT32 in their spec sheet it seemed worth taking a look at. The smaller capacity cards(32GB and under) ship pre formatted with FAT32. Larger cards like our sample ship formatted as exFAT. exFAT being recognized by android and most devices at this point should be the prefered choice as it allows files larger than 4GB.

Real world performance

Photo times with the card aren’t quite as fast as the 1800x from Lexar but provide a tangible boost over U1 cards I’ve tested. There were no issues adopting the card on the HTC10 adding it to the primary storage in a seamless manner.

Closing thoughts

Kingston manages to hit a sweet spot of performance and value with their new gold series microSD cards. At 43.23 these cards aren’t the cheapest available but the jump to U3 offers them a nice bump in performance. I encourage anyone looking for a card to pair to a new phone, or a performance boost on an existing phone that is on a budget to consider these cards.