SDXC slot compatibility

I'm having a hard time with your posts since you seem to hop here and there and apparently contradict things that you have said.

You said that you had tested and found that the Mac support 100 MB/s.

Apple specs say that they support up to 60 MB/s.

You claim that Apple's specs are not correct. It appears that your tests show that the Mac performs better than Apple's specs. So the Apple specs are not wrong since they meet 60 MB/s... they just understate the capability. Apple's specs do not claim to support the highest speeds capable of the UHS-I and UHS-II devices. I never said that they did.

You now claim that 60 MB/s is 104 MB/s. It is not. I never said that 60 MB/s is 100 MB/s. 60 MB/s is 60 MB/s.

Hi ApMaX

I Tested Lexar Professional 1000x in my iMAC mid 2011, but I just got 11 MB/s (Write) and 21.4 MB/s (READ).

I'm going to try this post

http://apple.stackexchange.com/questions/56159/how-can-i-speed-up-sd-card-writin g-speed-using-dev-disk-on-a-macbook-pro

Duane wrote:

The Apple specs that I linked to indicate 60 MB/s and you state that you have tested to 100 MB/s so it would seem that the Apple specs are correct.

Duane you have the patience of a Saint ! I would give you points for that alone.

p.s. It would be nice to hear back from the OP !

It is a hardware issue:

A list of UHS-II SD cards, readers, and cameras

https://www.pretzellogix.net/wp-content/uploads/2014/10/uhs-i-vs-uhs-ii.png

"It is, I think, quite clear that no current Apple product is shipping with support for UHS-II, which requires an additional row of hardware pins to support the double channel data speeds required by UHS-II."

Maybe, or maybe not. That is why I asked for real-world testing? Someone has latest Mac and can UHS-II reader to see real read/write speeds?

Let me add something to this discussion: I have just glimpsed into the SD slot of my Late 2013 MacBook Retina 13" and it seems to me that there is very little space left for those extra row of contacts. The card reaches about 16mm into the side of the notebook, minus 2mm for the aluminium shell. If I read the above image correctly, the UHS-II pins end at about 11mm, which gives us just 3mm space between the reader pins and the outer shell.

Maybe not worth the trouble from Apple's point of view?

I don't have an iMac with an internal card reader.

I mentioned above ... MacBook Pro Retina 15" mid-2014

If you send me a UHS-II card, I can perform the tests.

The Apple specs that I linked to indicate 60 MB/s and you state that you have tested to 100 MB/s so it would seem that the Apple specs are correct.

.

Based on these speed tests it looks to me like the answer is no UHS-II support in the 2015 MacBook Pro.

https://macperformanceguide.com/photography-Lexar_SDXC_1000X_256GB.html