Conclusion
Users looking for a decent high-capacity and high-speed SD memory card for a consumer or semi-professional device can look at our sequential throughput results and base their purchasing decision on them with confidence.
We also benchmarked access time and I/O performance for the sake of completeness, and to get a better impression of the strengths and weaknesses each product brings to the table. What we find is that most cards are poor performers if they're asked to execute a lot of I/O operations, particularly if there are writes involved. Most cards also really fail at random writes with small block sizes. Fortunately, while SD cards can be utilized as flexible storage devices or even system drives in the smallest systems, we categorically recommend against using SD memory cards for anything except sequential read or write operations.
In this category we have a definite winner: Kingston’s Ultimate XX series is by far the most expensive, but also by far the fastest SD memory card product line on the market. It delivers more than 60 MB/s sequential reads and 45 MB/s sequential writes. This is as much as you can get today, and it significantly reduces the time to transfer digital photography data or HD movies from your camera.
Bear in mind, however, that you also have to purchase a fast USB 3.0 card reader in order to take advantage of Kingston's performance. Otherwise, you'd be just fine sticking with USB 2.0-based hardware and almost any of the SD cards presented in the benchmark section. Thanks to great performance for many different enthusiast-oriented consumer devices, the Ultimate XX family receives the Recommended Buy Award.
Users on a budget do have other options, though. Like the Kingston Ultimate XX cards, SanDisk’s Extreme Pro is also based on the UHS bus, which technically supports up to 104 MB/s maximum bandwidth for SD card products. The Extreme Pro does not get faster than 45 MB/s, but it reaches the same speeds in sequential writes.
Many of the other cards with Class 10 or Class 6 performance classification typically perform better than their corresponding 10 MB/s or 6 MB/s minimum rated speeds. The Lexar Professional series, SanDisk’s Extreme (not the Pro), and a few others may not reach more than 24 MB/s maximum read speed, but they still demonstrate write performance that is quick enough for most devices requiring fast SD card storage.
