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SD Memory Card Performance And Standards

10 SDXC/SDHC Memory Cards, Rounded Up And Benchmarked
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We’re dealing with full-sized SD flash memory cards in this piece. These measure 32 x 24 x 2.1 mm, and they currently store up to 128 GB of data. There are many vendors and various speed classifications, but they all operate within the SD card memory standards SD 1.1, SD 2.0, or SD 3.0.

You typically find speed ratings like 133x or 300x printed on most of the products or product boxes. These are comparisons to the single-speed data transfer speeds of the good old CD-ROM. A 1x transfer rate is equivalent to 1.2 Mb/s or 150 KB/s.

Effectively, a 400x SD memory card can theoretically reach 400 * 0.15 MB/s, or 60 MB/s.

Don’t be blinded by these numbers though, as they typically reflect peak performance capabilities and do not reflect everyday throughput. To make matters worse, most vendors refer to read performance numbers and hide away the fact that the large majority of SD cards deliver much lower write performance.

The SD logo is very popular today.The SD logo is very popular today.

The initial SD cards compliant with revision 1.1 of the SD spec were limited to 2 GB, which is why SDHC (SD 2.0) was introduced to enable capacities of up to 32 GB. In addition to capacity, the SD 2.0 specification also provides performance classification to guarantee certain minimum throughput. There are four classes in the spec: Class 2, Class 4, Class 6, and Class 10. The number tells you the minimum transfer speeds in MB/s that can be sustained by the memory card.

We find that the Class ratings are more useful than the CD-ROM-based multiplier rating, as equivalent MB/s throughput is guaranteed and usually even exceeded by many SD cards. Speed ratings are important if you want to use your memory card on devices that require a certain minimum bandwidth, such as HD camcorders and digital SLR cameras. Once you want to store photos in RAW and JPEG mode, you need a fast memory card to support continuous shooting at several pictures per second.

The SD 3.0 (also known as SDXC) specification provides a ceiling of up to 2 TB. Although there are only a few SD memory cards with up 64 GB of capacity available, the SDXC standard also includes the modified UHS-I specification (Ultra HighSpeed I), supporting up to 104 MB/s. This is the successor to the High-Speed Bus I/F (Class 10) and Normal Bus I/F (Class 2, 4, 6), and it is the basis for products that can deliver more serious bandwidth. Be sure that any card reader you choose works with SDXC cards, as you cannot fully exploit SDXC cards with SDHC card readers.

Other Formats

In addition to conventional SD cards, you'll also find miniSD and microSD cards on the market. Those are well-suited to mobile devices like smartphones. They max out at 32 GB and they are electrically compatible with conventional SD cards, meaning that simple adapters allow you to access them. The miniSD form factor measures 20 x 21.5 x 1.4 mm. However, miniSD has never been very popular, and is on its way to disappear soon. The industry is either using SD or microSD.

microSD cards only measure 11 x 15 x 1.0 mm and are even smaller than a GSM cell phone SIM card. These are increasingly popular, as most smartphone designs utilize microSD cards as flexible storage. We currently find microSD cards at up to 32 GB, and it’s only a matter of time until they're also available at higher capacities. However, only few microSD cards deliver performance that is anywhere near the throughput we find on the devices tested in this article.

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  • -2 Hide
    douglasmeier , May 24, 2011 6:53 AM
    How yesterday can you be. Lexar has a USB 3.0 Card reader (http://www.lexar.com/products/lexar-professional-usb-30-dual-slot-reader?category=213) that supports SDXC UHS-I and CF UDMA cards (dual slots that work simultaneously and can write from one card to another) for $50. This isn't a cheapo card reader and is designed for professional photographers/videographers but has a theoretical max of 500MB/sec* These claims conflict with the published limits of the yet unavailable UHS-II cards which max out at 312MB/s. The 60MB/sec limit (per Lexar) is the USB 2.0 level. *the 500MB/s is their claim
  • 2 Hide
    tavix , May 24, 2011 8:45 AM
    Where are the Panasonic cards???
  • 1 Hide
    San Pedro , May 24, 2011 9:26 AM
    tavixWhere are the Panasonic cards???

    I was wondering same thing.
  • 1 Hide
    damianrobertjones , May 24, 2011 9:30 AM
    What I'd like to know, is that does leaving these cards in a laptop use battery life when the machine is OFF? It does on my Envy 13, resulting in a flat battery (probably a bug) and possibly on the TM2 as well.
  • 4 Hide
    damianrobertjones , May 24, 2011 9:33 AM
    __-_-_-__VERY disapointed not to see other cards. easy to for kingstone to be first! competition sucks. But there are way better!!!! I wonder how much kingstone paid tomshardware for this.just one example: 16GB Delkin Elite633 SDHC UHS-I 95MB/s read & 80MB/s write


    Maybe Toms asked others to provide cards and they didn't. it's not always as negative as you think!
  • 2 Hide
    briggsy147 , May 24, 2011 12:04 PM
    Ha, running a system off of one of these is exactly what I'm doing. I've got my Open Pandora OS on a Samsung Plus. I can't actually tell the difference between that and running the OS from the internal NAND memory of the machine.
  • -6 Hide
    ProDigit10 , May 24, 2011 12:21 PM
    1KiB = 1000 bytes, not 1024!
  • -2 Hide
    ProDigit10 , May 24, 2011 12:32 PM
    Quote:
    In the end, Kingston’s Ultimate XX line only has one weekness

    Indicating the minor errors as I read the article :-)
  • 1 Hide
    ProDigit10 , May 24, 2011 12:41 PM
    Sandisk extreme pro is probably the only type of card to put an OS on. Not only does it have faster IOPS, it also has a better ECC, which is vital for an operating system to work on!

    I'd not put any operating system on any other SD card; I've done it before, and it generally would take a couple of months before software read errors would appear!
  • 0 Hide
    nforce4max , May 24, 2011 1:49 PM
    Hmmm this is slower than what some compact flash cards have to offer. I bought on intending on using it as a cheap ssd for a old ibook.

    http://www.newegg.com/Product/Product.aspx?Item=N82E16820208529

    90mb/s read isn't to bad :)  not the fastest out there but certainly good. As for SD card in this review seam a little high but very nice roundup.
  • 0 Hide
    puddleglum , May 24, 2011 4:12 PM
    ProDigit101KiB = 1000 bytes, not 1024!

    I think the author was pointing out the difference between marketing kilobytes which is a power of 10 (10^3) versus computer kilobytes which is a power of 2 (2^10). Marketers have been advertising storage as a power of 10 for a long time now. What is new is that they are using KiB to indicate 2^10 and KB to indicate 10^3. This is suppose to replace the old designation based on case (mB for 10^3 and MB for 2^10) since people aren't always careful or aware of the case meaning.

    I'm not personally in favor of the new meaning, but the marketers have won out. You can see these KiB, MiB, ... definitions in wikipedia and some newer OSs.
  • 1 Hide
    yyrkoon , May 24, 2011 4:14 PM
    __-_-_-__VERY disapointed not to see other cards. easy to for kingstone to be first! competition sucks. But there are way better!!!! I wonder how much kingstone paid tomshardware for this.just one example: 16GB Delkin Elite633 SDHC UHS-I 95MB/s read & 80MB/s write

    tavixWhere are the Panasonic cards???


    Except there are flaws concerning your statement.

    First, the Lexar, and Sandisk memory cards have been around for more than 2 years. e.g. they are not based on some brand new technology. As a matter of a fact. I am willing to bet all the cards except the Kingston are all based on a few years old technology.

    Secondly, This is read only in a card reader, and not write capability in a camera. So if you're wanting to use this in a camera. Your camera wont perform any better.

    Most professional photographers will probably still use either the Lexar, or Sandisk memory cards. Mainly because they have been thoroughly tested in professional camera systems, and have been found to perform very well. Well, that is to say, those that even use SD card based Camera systems. Which will probably not be very many( except perhaps in secondary cameras ). Most photographers wanting/needing performance, will probably use a system that allows them to use CF media for the best performance.

    Transferring pictures to a computer after having taken them in a camera is often a far distant second concern. However, assuming this is important. Perhaps you could/should consider investing that money into CF media instead. Where is makes the most sense.

    For boot media, there are plenty of other options that make more sense( including, but not limited to CF media ). But in the event that you *have* to use SD media. Chances are very slim that the given system will support the latest/greatest cards to take full advantage of their speed capabilities.


  • 0 Hide
    Anonymous , May 24, 2011 4:49 PM
    How come San Disk Extreme, Class 10 is now in the bulk of the class 10 cards, while in the previous benchmarking article it was clearly standing out?
    http://www.tomshardware.com/reviews/compactflash-sdhc-class-10,2574-8.html
  • 0 Hide
    willwayne , May 24, 2011 10:05 PM
    ProDigit101KiB = 1000 bytes, not 1024!


    1 KB = 1 kilobyte = 10^3 = 1000
    1 KiB = 1 kibibyte = 2^10 = 1024
  • 2 Hide
    dalethepcman , May 24, 2011 10:36 PM
    The writer has come to a rather odd conclusion. In every test except peak read the Sandisk pro is similar or better than the Kingston. At half the price I would highly recommend the Sandisk over the Kingston any day.
  • 0 Hide
    douglasmeier , May 25, 2011 12:52 AM
    yyrkoonExcept there are flaws concerning your statement.First, the Lexar, and Sandisk memory cards have been around for more than 2 years. e.g. they are not based on some brand new technology. As a matter of a fact. I am willing to bet all the cards except the Kingston are all based on a few years old technology.Secondly, This is read only in a card reader, and not write capability in a camera. So if you're wanting to use this in a camera. Your camera wont perform any better.Most professional photographers will probably still use either the Lexar, or Sandisk memory cards. Mainly because they have been thoroughly tested in professional camera systems, and have been found to perform very well. Well, that is to say, those that even use SD card based Camera systems. Which will probably not be very many( except perhaps in secondary cameras ). Most photographers wanting/needing performance, will probably use a system that allows them to use CF media for the best performance. Transferring pictures to a computer after having taken them in a camera is often a far distant second concern. However, assuming this is important. Perhaps you could/should consider investing that money into CF media instead. Where is makes the most sense.For boot media, there are plenty of other options that make more sense( including, but not limited to CF media ). But in the event that you *have* to use SD media. Chances are very slim that the given system will support the latest/greatest cards to take full advantage of their speed capabilities.

    As I pointed out earlier. Lexar nows sells a USB 3.0 card reader that supports SD (in all its flavors, including UHS-I versions) and high speed CF media with two slots that even allow for reading/writing from one card to another. At only $50 from a respected company like Lexar, if I was a pro photographer transferring a lot of RAW files, buying one of their card readers would be a no brainer.
  • 0 Hide
    Anonymous , May 25, 2011 8:10 AM
    Tom, I think you have done a great job with this report, the mArket is a confusing jungle and your report will help greatly, any ideas for what can be done about all the fake cards out there?
    roger@abbeyland.co.uk
  • 0 Hide
    Anonymous , May 25, 2011 2:24 PM
    How does does the read/write performance of a very-high speed SD card compare on the listed USB 3.0 reader, the previously mentioned Lexar USB 3.0 reader and a selection of ExpressCard-based readers? I'm interested in a USB 3.0 reader, but without anything that currently has a USB 3.0 port, I'm stuck with some kind of adapter, so why not just skip to an ExpressCard version?
  • 0 Hide
    toughbook , May 25, 2011 4:43 PM
    The only companies I trust my data with is either Panasonic or Sandisk. For my ultra sensitive and secure data only goes on my IronKeys.

    Was Panasonic invited to this review?
  • 0 Hide
    toughbook , May 25, 2011 4:44 PM
    The only companies I trust my data with is either Panasonic or Sandisk. For my ultra sensitive and secure data only goes on my IronKeys.

    Was Panasonic invited to this review?
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