microSD slot spec for Acer Chromebook Spin 13 CP713-1WN

johnsutton

I'd like to buy the largest and fastest microSD card that is compatible with the slot on my Chromebook.  I assume the slot is SDXC but is it UHS?  And which: UHS-I, UHS-II or UHS-III?
Here is the info on the bottom of the machine:

Acer CP713 series
MODEL NO. N18Q2
CP713-1WN-5962 GE FR02 MFG Date : 2019/06/27
S/N: NXEFJEK003XXXXXXXX
SNID: XXXXX

Thanks!


Edited the content to hide sensitive information
Acer-Samuel

billsey

They don't seem to have those specs called out:

Card reader:

• Supports below card types and their corresponding capacity:
• Micro SD: 2GB
• Micro SDHC: 4GB min. / 64GB max.
• Micro SDXC: 64GB min. / 128GB max

Note that the 128GB max statement just means they didn't test with larger cards, I expect the larger ones would work fine. The SD controller is part of the chipset, the Intel Kaby Lake U, I wonder if Intel has specs on the speed supported?

billsey

They don't seem to have those specs called out:

Card reader:

• Supports below card types and their corresponding capacity:
• Micro SD: 2GB
• Micro SDHC: 4GB min. / 64GB max.
• Micro SDXC: 64GB min. / 128GB max

Note that the 128GB max statement just means they didn't test with larger cards, I expect the larger ones would work fine. The SD controller is part of the chipset, the Intel Kaby Lake U, I wonder if Intel has specs on the speed supported?

johnsutton

Thanks for that billsey.  Looking in chrome://system I find:

model name : Intel(R) Core(TM) i5-8250U CPU @ 1.60GHz

MCH: device id 5914 (rev 08) is Kabylake-R ULT
PCH: device id 9d4e (rev 21) is Kabylake-U iHDCP 2.2 Premium
IGD: device id 5917 (rev 07) is Kabylake-R ULT GT2

Googling suggests that the SD controller is related to PCH (rather than MCH or IGD?).  Intel have this document about their 8th gen processors:

https://www.intel.com/content/dam/www/public/us/en/documents/product-briefs/8th-gen-core-u-and-y-series-brief.pdf

which contains a table with the marvellously obtuse heading "The latest 8th Gen Intel® Core U-series processor, formerly codenamed Whiskey Lake, has the following feature advancements relative to its predecessor released in Q3'2017 formerly codenamed Kaby Lake-R".  The table has a row called Storage which gives:

KABY LAKE-R U42 (15W) : Intel® Optane SSDs/Memory, PCIe 3.0, SATA, SDXC 3.01, eMMC 5.0
WHISKEY LAKE U42 (15W) : Intel® Optane SSDs/Memory, PCIe 3.0, SATA, SD 3.0, eMMC 5.14

and in a table further down describing PCH-U KEY FEATURES there is:

Integrated SDXC (SDA 3.0) Controller : YES

Researching SD/SDA/SDXC 3.0/3.01 I find mention of both UHS-I (UHS-1) and UHS-III (UHS-3) but nothing definitive.  Note that AFAIU UHS-3 implies a second row of physical pins compared with UHS-1.

So, what to conclude?  It's probably safe to buy SDXC UHS-1 up to any size available, and within your budget!  It would be REALLY nice to know if the slot does in fact support UHS-3 as this implies 3x the write speed of UHS-1.

Having just escaped from the Apple ecosystem, I am struck by having had to spend >1 hour of my time researching something which Acer could have simply included in their documentation!

billsey

Ah, but if they said something like "SDXC 3.01 supporting speeds of 104MB/sec" someone would complain when their benchmark only showed 48MB/sec transfers. Realistically most people don't care, they're mostly interested in the capacity that works.

bugsyii

OK, so I've now tried 2 SDXC UHS-1 cards, both SanDisc, one 256GB and one 128.  Neither one will format, with the informative message "Could not format" .
Suggestions?  Other's experience?

bugsyii

Took the 16GB card out of my camera, put it in the slot, immediately recognized and I copied a file to and from it. It's a Hama brand Micro SD HC(?): 10 years old, at least.  So it seems it isn't the computer (Acer CP713).
?