iMac 5k 27 2019 sd card reader speed issue

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iMac 5k 27 2019 sd card reader speed issue

I have an iMac 5k 27 2019 on macOS Catalina 10.15.6

My SD card is SanDisk Extreme Pro SDHC/SDXC UHS-I Card 256GB [R:170 W:90]

I am moving multiple videos from multiple SD cards to my iMac every day for further processing. Each card has one mov file which is about 200GB. I am having trouble getting this SD card read speed to 170MB/s. I tried using Blackmagic speed test app to test my SD card and the result is capped at about 80-90MB/s read/write speed. Practical experience agree with that. Do I need to purchase a special SD card reader to achieve the rated read speed of 170MB/s? Is the built in SD card reader from iMac capped at 90MB/s? The system report shows my card reader has Link Speed 2.5GT/s, but I don't understand the equivalent MB/s of that. Thank you.

iMac Line (2012 and Later)

Posted on Aug 15, 2020 2:09 AM

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VikingOSX

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Aug 15, 2020 3:25 AM in response to JL___

Apple updated the SD Card reader spec for the newly released 2020 model to UHS-II. They give no I/O information on that 2019 model other than just having an SDXC slot, or how it will behave with an SDXC card over 64GB. You may need to research and invest in an external SDXC card reader that supports the UHS-II spec.

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iMac 5k 27 2019 sd card reader speed issue

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