The debate about MicroSD cards and WP7 phones continues, as we try and get to the bottom of what card you can use, and why it works over other ones.
It turns out that picking up “Class 4 or better” card isn’t actually a fix, because what WP7 needs is more than just speed. As posted in their support article:
Determining whether an SD card is Windows Phone 7 compliant is not a simple matter of judging its speed class. Several other factors, such as the number of random read/write operations per second, play a role in determining how well an SD card performs with Windows Phone 7 devices.
According to Engadget, the specifications need good “random access speed”, not “total throughput” which is what the Class rating accounts for. In other words, you might actually have to wait for a “Certified for Windows Phone 7″, as the type of cards that meet these specs are apparently only sold in bulk to manufacturers, not directly to consumers.