High capacity microSD cards offering 64 GB storage have been introduced almost a year ago at a rather high cost (more than $150/€150). Since then, prices have considerably dropped and these little cards are now quite affordable (under €50, £40 or $65) and offer a great accessory to increase your tablet storage space.
The SanDisk ULTRA 64GB card we are checking in this article offers a great Class 10 speed and follows the SDXC format (Secure Digital eXtended Capacity) that breaks the limit of 32 GB from the SDHC card standard.

SanDisk ULTRA 64GB microSDXC packaging and specifications (SDSDQU-064G-U46A product #)

SanDisk gives the following specifications for their product:

SanDisk 64GB ULTRA microSDXC Performance

The card is rated as Class 10, that asserts a minimum speed of 10 MB per second on non-fragmented sequential writes. UHS-I symbol relates to the Ultra-High Speed (UHS) that provides enhanced clock frequency compared to the original standards.

We used the following test setup to evaluate the SanDisk 64GB ULTRA microSDXC performance: x86-64 PC, 8 GB RAM, Windows 7, Transcend Multi-Card Reader M3 connected to computer thru USB 2.0 cable.

CrystalDiskMark 3.0.2 x64 benchmark
3 test runs, 100 MB test size

(MB/s = 1,000,000 bytes/s)

ATTO Disk Benchmark (DISK32) version 2.47 benchmark
0.5 to 8192 KB transfer size, Forced Write Access, I/O comparison 512 MB total length, random test pattern

On our test setup with these two benchmarks, we can see the SanDisk 64 GB is a little below the Class 10 specification, with sequential writing speed around 9.5 MB/s, the…