Hi !

I am planning to buy SDHC for my two smartbook and i have two questions before i make up my mind

1. Does it make difference to buy Extreme Pro card with 45MB/sec versus 30MB/sec for SDHC 32GB and which brand name works well with Genesi Smartbook


2. Since space is major issue, it will be okay for me to buy bigger size of SDHC card i.e 128GB. Will it work with smartbook.

Thanks

Walter.

Personally I use Kingston cards, and I never had a problem with them. I also have a 32GB Kingston, but that's a slower one, as anything faster at this size has a horror price tag...

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CzP
http://czanik.blogs.balabit.com/

I should point out that above 32GB the SD technology is no longer SDHC but SDXC. SDXC supports sizes up to 2TB.
http://en.wikipedia.org/wiki/Secure_Digital

As far as I know the Efika MX and Efika MX Smartbook only support SDHC.

Correct. The maximum supported size is 32GB.

The maximum speed the SDHC controller can support is also around 25MB/s (the manual states 200Mbit/s which is absolutely fixed as it's a 50MHz bus with a 4-bit data path) - if you are picking out cards, I'd stick to 32GB and I would pick a Kingston if at all possible if you are concerned about speed.

SD card "class" ratings or "100x" ratings are not well defined. While you can figure out a speed in megabytes per second, it is not clear from the manufacturer whether this is read, write, or from an optimized portion of the card. Kingston tend to give you write speeds (therefore read is somewhat faster, if they say it is 100x then it will do 18MB/s write and probably hit the limit for read. Sandisk shipping a 100x card will do maximum 18MB/s read, and probably significantly less (8-9MB/s tested here) in writing.

The "NNNx" rating is easy to work out - take the number (say 100), multiply it by 1.5 (which is megaBITS per second) and divide by 8 (to get megaBYTES). Class rating is simpler; 1 class rating = 1 megaBYTE per second (so class 10 = 10MB/s or 80Mb/s which is the same as 80x) but still, you have to guess whether that's maximum read, maximum write, sustained or burst, across the entire SD or just the first few blocks.. I never buy less than a Class 4 if I can help it, Class 10 may not be much faster in real life... complicated isn't it? D:

I would not expect much over 25MB/s from the controller, more likely something like 20MB/s (which is ~166x) from any card, no matter how well rated.

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Matt Sealey