Wednesday, January 25, 2006

Flash Card Speed Rating - The X-factor

You may have noticed that some flash cards, notably Compact Flash and Secure Digital, have X-ratings emblazoned on their packaging. Just like in the optical drive industry, the X-ratings give a measure of how fast the device can handle data.

So how fast really is a 133x SD card? A 1x speed rating corresponds to a transfer rate of 150 kilobytes (KB) per second, so a flash card rated at 133x can attain speeds of around 20 megabytes (MB) per second.

Some vendors use different names for their high-speed flash cards. Kingston labels their higher speed SD as Elite Pro SD (45x-50x) and SD Ultimate (120x-133x). On the other hand, Sandisk has their Ultra II SD (10MBps read/9MBps write) and Extreme III series (20MBps).

Now, tell me, what is the equivalent X-rating of a Sandisk Ultra II SD?

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