1. MindtakerWP's Avatar
    Hi guys.. I have one Lumia 950 with a PNY UHS U3 64GB, testing it can't reach more than 10.90MB/s of write speed...
    In my PC all seems work fine.

    What is the problem? Lumia limitation?

    EDIT: Lumia is on 10586.29 with the last FW update.
    01-22-2016 04:56 PM
  2. smartass1379's Avatar
    I have the same issue on .63 with original ATT firmware. Hoping the update will help
    01-22-2016 05:34 PM
  3. ByeVanno's Avatar
    I have the same issue on .63 with original ATT firmware. Hoping the update will help
    Hi might be off topic but how's the .63 going for you with the ATT firmware would you say its improved a good bit over .29 im wondering if I should go on the insider or not for that uodate
    01-22-2016 05:37 PM
  4. ashram's Avatar
    Does anyone actually know what the max read/write speed for the SD card slot on the 950 is? Because that could be causing your speeds as well. Can't assume just because you pop in a uhs 3 card that you'll get those speeds.
    01-23-2016 01:46 AM
  5. MindtakerWP's Avatar
    I have the same issue on .63 with original ATT firmware. Hoping the update will help


    Does anyone actually know what the max read/write speed for the SD card slot on the 950 is? Because that could be causing your speeds as well. Can't assume just because you pop in a uhs 3 card that you'll get those speeds.
    Should be better for 4K or 120 FPS, like in all others flagship smartphones. When I record 4K or 120 FPS on the SD, I have a little stuttering.
    Snapdragon 808 and 810 supports UHS-I U3.
    01-23-2016 06:21 PM
  6. ashram's Avatar




    Should be better for 4K or 120 FPS, like in all others flagship smartphones. When I record 4K or 120 FPS on the SD, I have a little stuttering.
    Snapdragon 808 and 810 supports UHS-I U3.
    well, i haven't had stuttering with 4k video... which encodes at a bitrate of around 40Mbps, which is around 5MBps (Mbps and MBps are different for those wondering). So 10MBps you're getting "should" be fine for 4k.

    Out of curiosity, what format is your sd card in? Fat32, NTFS or ExFat? Some people have had issues with ExFat (i haven't at all). Did you format the car before popping it in?

    Also, just because the chipset supports it, doesn't mean the device itself will. If 4k video is 5-6MBps, why would the phone need to go any faster? Granted, I have more speedtest experience using sd/microsd cards in DLSR's but the same applies. We also have no clue is some sort of caching is taking place or not. To top it off, any apps installed onto the sd card that can run in the background or any apps running in the background? Using the task switcher doesn't give you all the apps that are possibly open. after closing all apps, tap the back arrow a few times.? I know a couple of people who noticed better 4K recording once they made sure no apps were running.

    The samsung card I use (UHS1, 40MBps read) has had no issue with 4K recording.
    01-23-2016 10:17 PM
  7. MindtakerWP's Avatar
    well, i haven't had stuttering with 4k video... which encodes at a bitrate of around 40Mbps, which is around 5MBps (Mbps and MBps are different for those wondering). So 10MBps you're getting "should" be fine for 4k.

    Out of curiosity, what format is your sd card in? Fat32, NTFS or ExFat? Some people have had issues with ExFat (i haven't at all). Did you format the car before popping it in?

    Also, just because the chipset supports it, doesn't mean the device itself will. If 4k video is 5-6MBps, why would the phone need to go any faster? Granted, I have more speedtest experience using sd/microsd cards in DLSR's but the same applies. We also have no clue is some sort of caching is taking place or not. To top it off, any apps installed onto the sd card that can run in the background or any apps running in the background? Using the task switcher doesn't give you all the apps that are possibly open. after closing all apps, tap the back arrow a few times.? I know a couple of people who noticed better 4K recording once they made sure no apps were running.

    The samsung card I use (UHS1, 40MBps read) has had no issue with 4K recording.
    The format is exFAT (I did it from the phone, not before).

    I don't have any app installed on the SD. No other apps running in background when I record.



    EDIT: The "stuttering" happen only one time in the second 2 or 3.

    EDIT 2: Use this app! SD Card R/W Test

    64 MB File Size:

    Read: 120 to 152 MB/s
    Write: 13 to 20 MB/s

    5 MB File Size:

    Read: 20 to 55 MB/s
    Write: 10 to 15 MB/s
    Last edited by MindtakerWP; 01-24-2016 at 01:45 PM.
    01-23-2016 11:05 PM

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