Retina MBP card reader slow?

[JayMBP]

So I just got my hand on my 2.7 rMBP.

Everything is running smoothly and blazing fast.

The only exception seems to be the built-in SD card reader.

According to Anandtech's review, they had very good results on the reader. But when I tested mine with the Sandisk UHS-1 SD card (rated 45MB/s), the reader on MBP seems to max out around 20MB/s, while my Sandisk USB3.0 card reader has no problem getting almost to the limit.

Anyone know what is wrong?

Built-in

Sandisk USB3.0

 

[BB.King]

My 32GB SanDisk SD card works fine in the rmbp, I think it is the same as yours rated at 45MB/s read and write. I confirmed it with iStat menu 3 disk activity, the maximum speed was 48MB/s.

Maybe try this app or one of the many Windows ones if you have Windows installed on your machine.

 

[JayMBP]

I tested again with AJA system test. And it shows almost identical result.

Built-in reader topping at 20MB/s while USB3.0 at 42MB/s