32GB microsd cards

Search This thread
Lots of threads and lots of info.
This is purely my review ( based on the info i got from many places) on the topic.


How to test your memory card - see post 2


Hope this helps somebody
I will be updating the thread as more info comes in from users.

My recommendation after playing with all sorts of microsd cards and speeds is to get a sandisk 32gb card ( the new sandisk cards do not show a class speed , except for their ultra and extreme cards - This is their new policy )

Why this recommendation

- Randrom read write is the most important for speed during normal phone performance and i have seen sandisk cards have it the highest .
HERE IS A POST FROM SOMEONE IN XDA. Forgot the source
Class 2 and 4 cards have better random access speed and random read/write than class 6 or 10 cards in general. To get higher sequential write speeds, manufacturers sacrifice the random access speeds. That's just how it is.
The best all around card I've ever found is Sandisk class 4.
My 32gb Sandisk class 4 outperforms any other class 10 or 2 32gb card I've tested in the random access and random read/write speeds. That's what's most important when using with WP7 or Android when using it for apps or OS files that need to be accessed quickly. Class 6 and 10 cards are setup to initialize the area of the card that is about to be used to make the sequential write/read quicker, but it takes extra time in the beginning to do the initialization. If your using the card where you need to access small bits of info from various parts of card quickly, you will do best with class 2 or 4.
Most people seem to assume that the higher the class, the better the card is for everything, but that's not how it is. Different purposes need different kinds of speed... cards with higher sequential speeds have lower random speeds.

( quoted from one of the users in xda )

- Lexar class 10 ( I paid 94 $ for this :-( ) has terrible random speeds. The worst infact. Some of the other class 10 cards like kingston, patriot, topram have higher random speeds. However failure rate of some of these cards ( except kingston is high)

- Sandisk 32gb is relatively cheaper and very reliable.

- However if you are interested in regular copying of large files , like for eg : daily trnasfer of lots of music and movie files it might be better to get a class 10 card.

here are some of the links where cards are discussed about

newegg user reviews
http://www.newegg.com/Product/Product.aspx?Item=N82E16820220547


amazon user reviews
http://www.amazon.com/Lexar-MicroSD...dp_top_cm_cr_acr_txt?ie=UTF8&showViewpoints=1

xda discussion about various class of cards
http://xdaforums.com/showpost.php?p=13161740&postcount=26

I list I found of 32GB microSDHC cards:

Class 10
- Lexar 32GB High-Speed microSDHC Mobile (LSDMI32GBSBNAR)
- Patriot Signature 32GB Class 10 microSDHC Card (PSF32GMCSDHC10)
- Wintec FileMate Mobile Professional SDHC - Class 10 (3FMUSD32GBC10-R)
- TOPRAM 32GB Class 10 MicroSDHC Card (TRmicroSD32G_C10)

Class 6
- Komputerbay 32GB microSDHC Class 6

Class 4
- SanDisk MicroSDHC 32GB Class 4 Card (SDSDQM-032G-B35, SDSDQM-032G-B35A, SDSDQM-032G-B35N)
- Kingston 32GB microSDHC Flash Card (SDC4/32GB)
- Transcend 32GB microSDHC CARD Class 4 (TS32GUSDC4)
- Patriot Signature 32GB Class 4 (PSF32GMCSDHC43P)
- 3C Pro 32GB Class 4 microSDHC Card (3C_TF32G_C4)
- TOPRAM 32GB Class 4 microSDHC Card (TRmicroSD32G)

Class 2
- SanDisk microSDHC 32GB Card (SDSDQ-032G-A11M) [North American Version]
- SanDisk microSDHC 32GB Card (SDSDQ-032G-P36M) [Pacific Rim Version - should be the same as North America]
- SanDisk microSDHC 32GB Card (SDSDQ-032G-E11M) [related to MemoryVal?]
- Transcend 32GB microSDHC with SD Adapter (TS32GUSDHC2)
- Dane Elec 32GB microSDHC with SD Adaptor (DA-2IN1-32G-R)
- Duracell 32GB microSDHC with SD Adaptor (DU-2IN1-32G-R) [likely the same as the Dane Elec DA-2IN1-32G-R]

Editing to add more information

The link below is to the speed testing of many micro sd card. Very useful

http://forums.whirlpool.net.au/forum-replies.cfm?t=1582172


I am pasting the info from that thread here

screenshot20110611at120.png


screenshot20110611at120.png

____________________________________________________________________

Some test results posted in this thread

____________________________________________________________________

Patriot 32gb class 10

-----------------------------------------------------------------------
CrystalDiskMark 3.0.1 x64 (C) 2007-2010 hiyohiyo
Crystal Dew World : http://crystalmark.info/
-----------------------------------------------------------------------
* MB/s = 1,000,000 byte/s [SATA/300 = 300,000,000 byte/s]

Sequential Read : 19.282 MB/s
Sequential Write : 10.477 MB/s
Random Read 512KB : 19.071 MB/s
Random Write 512KB : 1.059 MB/s
Random Read 4KB (QD=1) : 7.335 MB/s [ 1790.7 IOPS]
Random Write 4KB (QD=1) : 0.247 MB/s [ 60.2 IOPS]
Random Read 4KB (QD=32) : 7.232 MB/s [ 1765.7 IOPS]
Random Write 4KB (QD=32) : 0.259 MB/s [ 63.2 IOPS]

Test : 100 MB [H: 47.0% (14.0/29.8 GB)] (x3) <All 0xFF, 1Fill>
Date : 2011/06/19 11:02:22
OS : Windows 7 Home Premium Edition [6.1 Build 7600] (x64)

-----------------------------------------------------------------------
Another test report for patriot class 10 card by user fyyzer
http://xdaforums.com/showpost.php?p=15704916&postcount=22

-----------------------------------------------------------------------
* MB/s = 1,000,000 byte/s [SATA/300 = 300,000,000 byte/s]

Sequential Read : 19.856 MB/s
Sequential Write : 17.332 MB/s
Random Read 512KB : 18.983 MB/s
Random Write 512KB : 0.724 MB/s
Random Read 4KB (QD=1) : 3.780 MB/s [ 922.9 IOPS]
Random Write 4KB (QD=1) : 0.006 MB/s [ 1.5 IOPS]
Random Read 4KB (QD=32) : 3.896 MB/s [ 951.2 IOPS]
Random Write 4KB (QD=32) : 0.006 MB/s [ 1.4 IOPS]

Test : 1000 MB [G: 5.8% (1.8/30.9 GB)] (x9)
Date : 2011/07/16 7:49:13
OS : Windows 7 SP1 [6.1 Build 7601] (x64)


____________________________________________________________________

____________________________________________________________________


SanDisk 8GB Class 6 for comparison, 2 years old.


-----------------------------------------------------------------------
CrystalDiskMark 3.0.1 x64 (C) 2007-2010 hiyohiyo
Crystal Dew World : http://crystalmark.info/
-----------------------------------------------------------------------
* MB/s = 1,000,000 byte/s [SATA/300 = 300,000,000 byte/s]

Sequential Read : 21.241 MB/s
Sequential Write : 17.626 MB/s
Random Read 512KB : 20.846 MB/s
Random Write 512KB : 4.629 MB/s
Random Read 4KB (QD=1) : 5.356 MB/s [ 1307.5 IOPS]
Random Write 4KB (QD=1) : 0.052 MB/s [ 12.7 IOPS]
Random Read 4KB (QD=32) : 5.484 MB/s [ 1338.8 IOPS]
Random Write 4KB (QD=32) : 0.058 MB/s [ 14.2 IOPS]

Test : 100 MB [H: 89.2% (6939.2/7782.5 MB)] (x3)
Date : 2011/06/19 0:47:33
OS : Windows 7 Ultimate Edition SP1 [6.1 Build 7601] (x64)

____________________________________________________________________
____________________________________________________________________



32GB Class 4 Sandisk.


Tested results when I received it today and thought I would post the results in case anyone else is considering purchasing from the same source.

-----------------------------------------------------------------------
CrystalDiskMark 3.0.1 x64 (C) 2007-2010 hiyohiyo
Crystal Dew World : http://crystalmark.info/
-----------------------------------------------------------------------
* MB/s = 1,000,000 byte/s [SATA/300 = 300,000,000 byte/s]

Sequential Read : 20.071 MB/s
Sequential Write : 6.088 MB/s
Random Read 512KB : 19.716 MB/s
Random Write 512KB : 0.625 MB/s
Random Read 4KB (QD=1) : 3.234 MB/s [ 789.5 IOPS]
Random Write 4KB (QD=1) : 1.467 MB/s [ 358.2 IOPS]
Random Read 4KB (QD=32) : 3.164 MB/s [ 772.4 IOPS]
Random Write 4KB (QD=32) : 0.150 MB/s [ 36.5 IOPS]

Test : 1000 MB [E: 1.9% (0.6/29.7 GB)] (x5)
Date : 2011/06/27 19:34:44
OS : Windows 7 Home Premium Edition SP1 [6.1 Build 7601] (x64)

29.71gb Capacity

SD Tools results:

writing speed 6.2mb/s
reading speed 21.7mb/s

More testing of sandisk 32gb class 4 card

http://xdaforums.com/showpost.php?p=16472035&postcount=65
from user freeze888

http://xdaforums.com/showthread.php?p=15269669
from user Shudushi

View attachment 656461 View attachment 656462

From user cajunflavoredbob
http://xdaforums.com/showpost.php?p=15713401&postcount=25

Clipboard01-2.jpg
[/QUOTE]


____________________________________________________________________
____________________________________________________________________

Just adding somemore info on some the cards i have

sandisk32gbclass4.png


sandisk16gbclass2.png


lexar32gbclass10.png





ADAta sd card Thanks to jesus_c
http://xdaforums.com/showpost.php?p=15700083&postcount=20

http://twitpic.com/5q0ryp





Test report for other class of cards

1. Thanks to vicedens2002

http://xdaforums.com/showpost.php?p=15700162&postcount=21

- Samsung 8GB class 6
- Sandisk 1GB
- Windows drive 60GB Class 3072 - OOps i wish I had this in my phone ;-)


FINALLY 64GB CARD
http://www.geek.com/articles/mobile/kingmax-intros-worlds-first-64gb-microsd-card-20110526/
 
Last edited:
How to test your memory card


1)Crystal bench mark for finding the random write speeds
2) H2testw 1.4 which tests to see if your card has genuine capacity
3) SD Formatter for SDHC This software formats all SD memory cards, SDHC memory cards

Thanks to user Szczepanik
http://xdaforums.com/showpost.php?p=15913944&postcount=45



Samsung has recently announced a 32gb class10 card.
The specs for speed looks very nice

http://www.engadget.com/2011/06/30/samsung-announces-32gb-microsd-card-capable-of-12mbps-write-spee/
 
Last edited:

cyRq

Senior Member
Mar 3, 2011
169
60
fragxperts.pl
Patriot LX Micro SDHC 8GB Class 10 (PSF8GMCSDHC1)
tested on Windows Vista SP2 x86

Code:
--------------------------------------------------
CrystalDiskMark 2.2 (C) 2007-2008 hiyohiyo
      Crystal Dew World : http://crystalmark.info/
--------------------------------------------------

   Sequential Read :   16.772 MB/s
  Sequential Write :    9.199 MB/s
 Random Read 512KB :   16.726 MB/s
Random Write 512KB :    0.941 MB/s
   Random Read 4KB :    3.217 MB/s
  Random Write 4KB :    0.008 MB/s

         Test Size : 100 MB
              Date : 2011/07/03 15:13:46

I see the 32GB version is much faster in random acesses. Just for the record - the 8GB version sucks :p
 
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jesus_c

Senior Member
Mar 15, 2007
829
409
44
MKADsk
Great speeds.
Will add that to first post
It would be great if u could do a detailed test with crystalmark application.

A-DATA MicroSDHC 32GB class 10 [AUSDH32GCL10-RM3BKBL]

tested on my old netbook lenovo s10-2 with windows 7 x86 sp1 2GB RAM
used a-data microsd-usb2.0 adapter
second test in my phone with sdcardspeedfix (2048KB)
 

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  • 91
    Lots of threads and lots of info.
    This is purely my review ( based on the info i got from many places) on the topic.


    How to test your memory card - see post 2


    Hope this helps somebody
    I will be updating the thread as more info comes in from users.

    My recommendation after playing with all sorts of microsd cards and speeds is to get a sandisk 32gb card ( the new sandisk cards do not show a class speed , except for their ultra and extreme cards - This is their new policy )

    Why this recommendation

    - Randrom read write is the most important for speed during normal phone performance and i have seen sandisk cards have it the highest .
    HERE IS A POST FROM SOMEONE IN XDA. Forgot the source
    Class 2 and 4 cards have better random access speed and random read/write than class 6 or 10 cards in general. To get higher sequential write speeds, manufacturers sacrifice the random access speeds. That's just how it is.
    The best all around card I've ever found is Sandisk class 4.
    My 32gb Sandisk class 4 outperforms any other class 10 or 2 32gb card I've tested in the random access and random read/write speeds. That's what's most important when using with WP7 or Android when using it for apps or OS files that need to be accessed quickly. Class 6 and 10 cards are setup to initialize the area of the card that is about to be used to make the sequential write/read quicker, but it takes extra time in the beginning to do the initialization. If your using the card where you need to access small bits of info from various parts of card quickly, you will do best with class 2 or 4.
    Most people seem to assume that the higher the class, the better the card is for everything, but that's not how it is. Different purposes need different kinds of speed... cards with higher sequential speeds have lower random speeds.

    ( quoted from one of the users in xda )

    - Lexar class 10 ( I paid 94 $ for this :-( ) has terrible random speeds. The worst infact. Some of the other class 10 cards like kingston, patriot, topram have higher random speeds. However failure rate of some of these cards ( except kingston is high)

    - Sandisk 32gb is relatively cheaper and very reliable.

    - However if you are interested in regular copying of large files , like for eg : daily trnasfer of lots of music and movie files it might be better to get a class 10 card.

    here are some of the links where cards are discussed about

    newegg user reviews
    http://www.newegg.com/Product/Product.aspx?Item=N82E16820220547


    amazon user reviews
    http://www.amazon.com/Lexar-MicroSD...dp_top_cm_cr_acr_txt?ie=UTF8&showViewpoints=1

    xda discussion about various class of cards
    http://xdaforums.com/showpost.php?p=13161740&postcount=26

    I list I found of 32GB microSDHC cards:

    Class 10
    - Lexar 32GB High-Speed microSDHC Mobile (LSDMI32GBSBNAR)
    - Patriot Signature 32GB Class 10 microSDHC Card (PSF32GMCSDHC10)
    - Wintec FileMate Mobile Professional SDHC - Class 10 (3FMUSD32GBC10-R)
    - TOPRAM 32GB Class 10 MicroSDHC Card (TRmicroSD32G_C10)

    Class 6
    - Komputerbay 32GB microSDHC Class 6

    Class 4
    - SanDisk MicroSDHC 32GB Class 4 Card (SDSDQM-032G-B35, SDSDQM-032G-B35A, SDSDQM-032G-B35N)
    - Kingston 32GB microSDHC Flash Card (SDC4/32GB)
    - Transcend 32GB microSDHC CARD Class 4 (TS32GUSDC4)
    - Patriot Signature 32GB Class 4 (PSF32GMCSDHC43P)
    - 3C Pro 32GB Class 4 microSDHC Card (3C_TF32G_C4)
    - TOPRAM 32GB Class 4 microSDHC Card (TRmicroSD32G)

    Class 2
    - SanDisk microSDHC 32GB Card (SDSDQ-032G-A11M) [North American Version]
    - SanDisk microSDHC 32GB Card (SDSDQ-032G-P36M) [Pacific Rim Version - should be the same as North America]
    - SanDisk microSDHC 32GB Card (SDSDQ-032G-E11M) [related to MemoryVal?]
    - Transcend 32GB microSDHC with SD Adapter (TS32GUSDHC2)
    - Dane Elec 32GB microSDHC with SD Adaptor (DA-2IN1-32G-R)
    - Duracell 32GB microSDHC with SD Adaptor (DU-2IN1-32G-R) [likely the same as the Dane Elec DA-2IN1-32G-R]

    Editing to add more information

    The link below is to the speed testing of many micro sd card. Very useful

    http://forums.whirlpool.net.au/forum-replies.cfm?t=1582172


    I am pasting the info from that thread here

    screenshot20110611at120.png


    screenshot20110611at120.png

    ____________________________________________________________________

    Some test results posted in this thread

    ____________________________________________________________________

    Patriot 32gb class 10

    -----------------------------------------------------------------------
    CrystalDiskMark 3.0.1 x64 (C) 2007-2010 hiyohiyo
    Crystal Dew World : http://crystalmark.info/
    -----------------------------------------------------------------------
    * MB/s = 1,000,000 byte/s [SATA/300 = 300,000,000 byte/s]

    Sequential Read : 19.282 MB/s
    Sequential Write : 10.477 MB/s
    Random Read 512KB : 19.071 MB/s
    Random Write 512KB : 1.059 MB/s
    Random Read 4KB (QD=1) : 7.335 MB/s [ 1790.7 IOPS]
    Random Write 4KB (QD=1) : 0.247 MB/s [ 60.2 IOPS]
    Random Read 4KB (QD=32) : 7.232 MB/s [ 1765.7 IOPS]
    Random Write 4KB (QD=32) : 0.259 MB/s [ 63.2 IOPS]

    Test : 100 MB [H: 47.0% (14.0/29.8 GB)] (x3) <All 0xFF, 1Fill>
    Date : 2011/06/19 11:02:22
    OS : Windows 7 Home Premium Edition [6.1 Build 7600] (x64)

    -----------------------------------------------------------------------
    Another test report for patriot class 10 card by user fyyzer
    http://xdaforums.com/showpost.php?p=15704916&postcount=22

    -----------------------------------------------------------------------
    * MB/s = 1,000,000 byte/s [SATA/300 = 300,000,000 byte/s]

    Sequential Read : 19.856 MB/s
    Sequential Write : 17.332 MB/s
    Random Read 512KB : 18.983 MB/s
    Random Write 512KB : 0.724 MB/s
    Random Read 4KB (QD=1) : 3.780 MB/s [ 922.9 IOPS]
    Random Write 4KB (QD=1) : 0.006 MB/s [ 1.5 IOPS]
    Random Read 4KB (QD=32) : 3.896 MB/s [ 951.2 IOPS]
    Random Write 4KB (QD=32) : 0.006 MB/s [ 1.4 IOPS]

    Test : 1000 MB [G: 5.8% (1.8/30.9 GB)] (x9)
    Date : 2011/07/16 7:49:13
    OS : Windows 7 SP1 [6.1 Build 7601] (x64)


    ____________________________________________________________________

    ____________________________________________________________________


    SanDisk 8GB Class 6 for comparison, 2 years old.


    -----------------------------------------------------------------------
    CrystalDiskMark 3.0.1 x64 (C) 2007-2010 hiyohiyo
    Crystal Dew World : http://crystalmark.info/
    -----------------------------------------------------------------------
    * MB/s = 1,000,000 byte/s [SATA/300 = 300,000,000 byte/s]

    Sequential Read : 21.241 MB/s
    Sequential Write : 17.626 MB/s
    Random Read 512KB : 20.846 MB/s
    Random Write 512KB : 4.629 MB/s
    Random Read 4KB (QD=1) : 5.356 MB/s [ 1307.5 IOPS]
    Random Write 4KB (QD=1) : 0.052 MB/s [ 12.7 IOPS]
    Random Read 4KB (QD=32) : 5.484 MB/s [ 1338.8 IOPS]
    Random Write 4KB (QD=32) : 0.058 MB/s [ 14.2 IOPS]

    Test : 100 MB [H: 89.2% (6939.2/7782.5 MB)] (x3)
    Date : 2011/06/19 0:47:33
    OS : Windows 7 Ultimate Edition SP1 [6.1 Build 7601] (x64)

    ____________________________________________________________________
    ____________________________________________________________________



    32GB Class 4 Sandisk.


    Tested results when I received it today and thought I would post the results in case anyone else is considering purchasing from the same source.

    -----------------------------------------------------------------------
    CrystalDiskMark 3.0.1 x64 (C) 2007-2010 hiyohiyo
    Crystal Dew World : http://crystalmark.info/
    -----------------------------------------------------------------------
    * MB/s = 1,000,000 byte/s [SATA/300 = 300,000,000 byte/s]

    Sequential Read : 20.071 MB/s
    Sequential Write : 6.088 MB/s
    Random Read 512KB : 19.716 MB/s
    Random Write 512KB : 0.625 MB/s
    Random Read 4KB (QD=1) : 3.234 MB/s [ 789.5 IOPS]
    Random Write 4KB (QD=1) : 1.467 MB/s [ 358.2 IOPS]
    Random Read 4KB (QD=32) : 3.164 MB/s [ 772.4 IOPS]
    Random Write 4KB (QD=32) : 0.150 MB/s [ 36.5 IOPS]

    Test : 1000 MB [E: 1.9% (0.6/29.7 GB)] (x5)
    Date : 2011/06/27 19:34:44
    OS : Windows 7 Home Premium Edition SP1 [6.1 Build 7601] (x64)

    29.71gb Capacity

    SD Tools results:

    writing speed 6.2mb/s
    reading speed 21.7mb/s

    More testing of sandisk 32gb class 4 card

    http://xdaforums.com/showpost.php?p=16472035&postcount=65
    from user freeze888

    http://xdaforums.com/showthread.php?p=15269669
    from user Shudushi

    View attachment 656461 View attachment 656462

    From user cajunflavoredbob
    http://xdaforums.com/showpost.php?p=15713401&postcount=25

    Clipboard01-2.jpg
    [/QUOTE]


    ____________________________________________________________________
    ____________________________________________________________________

    Just adding somemore info on some the cards i have

    sandisk32gbclass4.png


    sandisk16gbclass2.png


    lexar32gbclass10.png





    ADAta sd card Thanks to jesus_c
    http://xdaforums.com/showpost.php?p=15700083&postcount=20

    http://twitpic.com/5q0ryp





    Test report for other class of cards

    1. Thanks to vicedens2002

    http://xdaforums.com/showpost.php?p=15700162&postcount=21

    - Samsung 8GB class 6
    - Sandisk 1GB
    - Windows drive 60GB Class 3072 - OOps i wish I had this in my phone ;-)


    FINALLY 64GB CARD
    http://www.geek.com/articles/mobile/kingmax-intros-worlds-first-64gb-microsd-card-20110526/
    15
    How to test your memory card


    1)Crystal bench mark for finding the random write speeds
    2) H2testw 1.4 which tests to see if your card has genuine capacity
    3) SD Formatter for SDHC This software formats all SD memory cards, SDHC memory cards

    Thanks to user Szczepanik
    http://xdaforums.com/showpost.php?p=15913944&postcount=45



    Samsung has recently announced a 32gb class10 card.
    The specs for speed looks very nice

    http://www.engadget.com/2011/06/30/samsung-announces-32gb-microsd-card-capable-of-12mbps-write-spee/
    7
    When I rang Technical Support at SanDisk to ask about cards, this is what they told me. The guy I spoke to seemed knowledgeable, but of course this info might be incomplete or maybe just his understanding of the situation...

    First up, "Mobile Ultra" and "Ultra" are the same card, the name difference was just for marketing purposes, to show people the card could be used in mobiles. However the plan backfired and people thought they couldn't use "Mobile Ultra" in their camera, so the name was dropped.

    To decipher the codes such as SDSDQUA-032G-U46A:

    SDSD=sd card

    Q =class 4 (black) available in 2,4,8,16,32GB
    QY=class 6 "Ultra" (red & grey) available in 4GB (8,16,32gb discontinued but still on sale)
    QU=?
    QUA=class 10 "Ultra" 8,16,32=SDHC 64=SDXC* (UHS-I = UHS class 1 = 10mb/s #)
    QUI=class 10 "Ultra" apparently "designed for cameras" and NOT the same card (black packaging)

    -000G=GB

    -U46=EU packaging@
    -A11=US packaging@
    -FFP=Amazon frustration free packaging@

    A=picture of android on package

    NOTES
    * Compatible devices only
    # If used in a non UHS-I compliant phone, it will revert to class 10
    @ If it doesn't have a code at the end, it's not covered by SanDisk warranty
    3
    Thank you for information :) .
    I dont like it :( , its sucks that higher class is not better in all ways.
    But then, why people here in xda keep saying that class4 is better than class6/10 in using applications, you say that it depends on random read speed. We see that random read speed is higher in class6
    class6
    Random Read 4KB (QD=1) : 5.356 MB/s [ 1307.5 IOPS]
    Random Read 4KB (QD=32) : 5.484 MB/s [ 1338.8 IOPS]
    vs.
    class4
    Random Read 4KB (QD=1) : 3.234 MB/s [ 789.5 IOPS]
    Random Read 4KB (QD=32) : 3.164 MB/s [ 772.4 IOPS]

    Card manufacturers sacrifice random speed in order to gain sequential speed boosts in their cards. This generally means that the random speeds get slower as the sequential speeds get higher. The speeds vary depending on the card reader, PC, and card manufacturer. There isn't just one card to rule them all. You have to find out for yourself which card is better for you.

    Random speeds are even more critical in WP7 devices, which need a very high random speed to use the cards properly. In Android and other operating systems, you need to decide what your primary use for the card is. If you are looking to take lots of HD video, pictures, or watch lots of movies on your device, then a higher class card is much better for that. If you mostly just play games or use apps, then a lower class card is better for you.

    As I mentioned, not all cards will give you the same results as others who have posted here. I use Class 4 SanDisk cards as I have a HD2 that I use for running WM, Android, or WP7 depending on how I feel at the time. Running WP7 at all requires that I have high random speeds, so I have to use a low class card anyway. Even on Android, I store most apps on my SD card, so a low class card is better here too. I rarely watch movies or even record video on it. My camera takes decent enough pictures at 5MP that a low class card doesn't slow it down any. Even on WM, that operating system is optimized for lower class cards, since that's what was available at the time.

    Anyway, there are 5 classes of cards from class 2 up to class 10. If you want one in the middle, then get a class 6. This is just going to give to low numbers in both categories, though, so I would suggest getting either a class 4 or class 10, depending on what you do the most.
    3
    How about android phones. Do they rely more on random than sequential?

    WP7 bonds the SD cards with the NAND memory in a sort of RAID 0 array. Because the memory acts as one single unit, rather than separate storage and internal memory environments, it needs a memory format with high random speeds to be able to run apps, cache data, and do other things that the internal NAND memory on other devices would normally handle.

    Android devices use the SD card as a memory card. You need to decide which class to get based on what you mainly use the card for. Running apps and games from the card would be better with a lower class card. Recording HD video, transferring files, and saving pictures will be faster with higher class cards.