The SD Card Association has announced the UHS-III standard that allows for maximum data rates twice as fast as the current UHS-II interface. The new interface will allow cards to transfer data at up to 624MB/s and will be used in both SD and Micro SD cards.
The UHS-III interface on future devices will be fully backwards compatible with existing SD cards. The cards themselves will include a second row of pins, so will be physically identical to current UHS-II.
The adoption of UHS-III branding may cause further confusion with the U3 speed rating that appears on many current cards. This may be mitigated if UHS-III cards prove to be capable of higher guaranteed sustained write speeds, allowing them to wear the ‘V60’ or faster ‘video speed class’ branding announced in 2016.
Although an increasing number of cameras (including many recent Fujifilm models, the Olympus E-M1 Mark II and Panasonic GH5) can make full use of the faster maximum transfer speeds of UHS-II cards, we’ve not yet seen any cards that can promise to sustain writing of data at faster than the 30MB/s promised by U3 ratings. This means all the x-hundred megabyte per second write speeds promised on current cards are useful only for bursts of stills: any camera trying to record video at data rates of above 30MB/s (240 mbps) run the risk of stuttering during recording.
Source: DP Review
