It’s becoming more and more clear why Microsoft tried to prohibit accessible microsd cards in Windows Phone. With all of the complaints that are coming from users and what appears to be a lack of testing until the phones were released it’s gotten ugly. So there are now certified MicroSD cards from Sandisk and they’re actually class2 cards:

Here’s the Kingston certified cards (including my Kingston 32gb class 4 card) that range in class:

But why is it so difficult to know what cards will work? I mean, if it’s a class 2 or higher it should work, right? Nope

Unfortunately, it is hard to determine which SD card is “fast” and which is “slow” without a lot of testing, and the advertised “class” of an SD card has almost nothing to do with how well it will perform in a phone. SD card “class” measures how quickly an SD card can save a single large file such as a photo (think of this like you would think about a car’s top speed). Windows Phone’s performance is more affected by how quickly the SD card can save a whole bunch of tiny files (think of this like you would think about a car’s performance in an obstacle course). Don’t fool yourself into thinking that any old SD card will work or that a higher-class SD card will make your phone work better. Microsoft tested a whole bunch of different SD cards. Very few performed well enough to be approved for use in the phone. Other SD cards may work correctly, but the SD card’s “class” won’t be very helpful in predicting how the card will perform in the phone.

While we’re at it, there’s one more warning. If you insert a card into your phone then the card is encrypted and it’s effectively bricked. It will not be usable in a PC or other phones. Apparently if you have a Symbian phone you can unlock them…but that’s probably harder to find than a four leaf clover in the US. Let’s sum this up with the words of the infamous Ramon:

This is starting to annoy the F@K!!!!! out of me!!!!
let me see if i got this right. Microsoft designed an os with wide span memory in mind. The ideology of "save to storage card" simply doesn’t apply because the OS sees it all as one huge storage pool. Great. works for apple…and it will work for Microsoft. 
But nooooo…. the carriers want to bitch and moan to the OEM’s about cost of devices. So OEM’s go back to Microsoft bitching and moaning about expandable memory. And Microsoft being Microsoft…changes plans mid flight and allows it. Bending over backwards again to please people…and now look at what the f@k is going on. 
All because carriers want to save a few dollars on the devices…no one knows what the f will work. and Microsoft gets the bad rep for it. f-ing shame.


  1. Ramon, your words are clearer than my screen protector. OEM’s should have just loaded up the devices with 16GB (should be a minimum requirement) or 32GB and been done with it. As you said, it worked for Apple.

    Just what Microsoft needed at launch. What a nightmare.

    And I will beat you to the punch this time. F@k Apple!!!

  2. I had the Sandisc 32 mentioned here, and after 3 days (when sync data went over 8GB and started hitting the card possibly) it started rebooting randomly, glitching, then locked the phone (over 2 days). My card was the:
    NewEgg item number N82E16820171454

    …so I would be wary of this list until Samsung certifies. (as of now they’ve only certed the 8GB, is that right?).

    Just wanted to get that out there, because that card killed the phone and is worthless now since it won’t read in any other device.
    I’ve since ordered the Kingston 32GB/c4 and see that it’s listed here, but I’m waiting for official word before I try THAT again. (Love the phone, though!)

  3. Some comments on the fact that the SD card is tied to the phone and can’t be used anywhere else after this:

    This seems to be the MMC/SD card locking functionality described in the SD hardware spec.
    I described some background and my thoughts on this in a bit more detail here:

    Also it seems to me that with MMC unlock clips you should be able to “force erase” the SD card as well in case you don’t have a Symbian phone handy :)
    For example this thing:,browse,id_gr,326,menu_mode,categories.html

  4. I’m kind of amazed that MS decided to use sd cards as the main storage source. I have had so much trouble with corruption on my 16 gb sandisk card over the last 2 years, that there is no way I would trust it as the main device storage. Thank the lord for wizcode scandisk (and sk schema); I scan it every night, and get errors a couple times per month. I’m not all surprised that people have issues, particularly with random reboots. I hope the system has a built in method to correct file and directory errors.

  5. I send an inquiry to Kingston Support about their compatible card listing and here is the answer I got:

    Thank you for your inquiry. This card matches the spec that the phone requires and should most likely work for you. There is no certification with this phone, AT&T, Microsoft, and our part.

    Definitely not conclusive. Fact is that tonight I am going to have my phone and my Kingstong Class 4 32GB microSD sitting one next to the other and will have to decide what to do…

  6. […] heeft wel een micro SD card slot. Niet alle micro SD cards zouden er op werken, enkel high speed, (An Update On Windows Phone Storage Cards (And an Explanation) Sandisk and Kingston Are Certified). En er zou een hard reset moeten gedaan worden elke keer als de kaart er in of uit wordt gehaald […]

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