From the Sandisk SDHC Extreme 32GB, there are two models that differ visually far right of the SDHC logo to a "Roman one".
- Without "Roman one" is no longer produced SDSDX3-032G-A31 (Note the number 3 in the sixth position and ending 31). This only works for the old SD-SD 2.0 specifications and reaches the speed class 10 (see the circled 10 left on the map).
- With "Roman one" is the current SDSDX-032G-X46, which additionally supports the new bus interface UHS-I. When a camera this UHS-I support, then this card can write more than 30 MB / s and read. In the many cameras that do not support the UHS-I card with Speed Class 10 works (see the circled 10 left on the map). According to the statement in c't 18/2011 is limited these older SD standard to about 25 MB / s.
Now, if you use such a card with a USB reader and makes speed measurements, then the slow USB2 interface and / or the lack of UHS-I support will make the measurement useless. A reader with USB3 and also UHS-I support, for example, Sandisk ImageMate All-in-One Reader 3.0, should be used for speed measurements.
- The more expensive "Extreme Pro" models offer not only faster flash devices, but also guarantee compliance with the so-called UHS Speed Class 1. Visually, the one represented by a number within a letter U. According to the statement in the English Wikipedia allows this class the transfer of 50 MB / s. Again, only making a speed measurement make sense if the reader supports UHS-I.
By the way, I decided to purchase the Extreme card, because they are the much lower write access time (just under 4 ms) than other manufacturers in accordance with test of the magazine CHIP. For example, Transcend has been tested with more than 307 ms.
