USB 3.0 slow on my brand new iMac

tarsierspectral

macrumors regular
Original poster
Aug 13, 2010
170
0
Why are the USB 3.0 ports so slow on my brand new iMac? I am transfarring from an SD card using Delkin Devices card reader and first it takes about 30sec to about 1min for the card to appear on my desktop and then it gives me the time of like 8 hours to transfer 6GB than it reduces and ends up being way less BUT when I plug the same reader, the same card to my Mac Pro which is 3 years old and doesn't even support USB 3.0 the card shows up on the desktop immediately and I am able to open it and look at files and the transfer is super fast. What's wrong with my new machine?
 

iamgalactic

macrumors regular
Apr 21, 2010
180
58
what speed is your card reader? it may be USB 2 - which means it can't get USB 3 speeds. also, there may be some backward compatibility issues with that device...

go to apple>about this mac>system report>USB

is your card reader under the USB 3.0 section?
 

tarsierspectral

macrumors regular
Original poster
Aug 13, 2010
170
0
Contact Delkin and explain what's happening. Reviews I've red about this card reader said the company is responsive, but any fixes require sending the reader back for a factory re-flash.
But it works fine on Mac Pro
 

gnasher729

macrumors P6
Nov 25, 2005
16,573
3,151
It's most likely a matter of the SD card itself. USB 2 can transmit up to about 35 Megabyte per second on a new Mac; if something is slower than that then it is a problem with the reader or the card. If the card is slow, then USB 3.0 won't help one bit, and a fast card reader won't help either.

Basically, your card can do X megabyte per second, your card reader can do Y megabyte per second, the Mac can do 35 megabyte per second with USB 2 and a lot more with USB 3, and your actual speed is the slowest of the three.
 

tarsierspectral

macrumors regular
Original poster
Aug 13, 2010
170
0
It's most likely a matter of the SD card itself. USB 2 can transmit up to about 35 Megabyte per second on a new Mac; if something is slower than that then it is a problem with the reader or the card. If the card is slow, then USB 3.0 won't help one bit, and a fast card reader won't help either.

Basically, your card can do X megabyte per second, your card reader can do Y megabyte per second, the Mac can do 35 megabyte per second with USB 2 and a lot more with USB 3, and your actual speed is the slowest of the three.
But why is it fine on my Mac Pro?
 

jmhart

macrumors regular
Jun 14, 2012
127
0
Why are the USB 3.0 ports so slow on my brand new iMac? I am transfarring from an SD card using Delkin Devices card reader and first it takes about 30sec to about 1min for the card to appear on my desktop and then it gives me the time of like 8 hours to transfer 6GB than it reduces and ends up being way less BUT when I plug the same reader, the same card to my Mac Pro which is 3 years old and doesn't even support USB 3.0 the card shows up on the desktop immediately and I am able to open it and look at files and the transfer is super fast. What's wrong with my new machine?
I'd try a different USB 3.0 reader...if possible one that is Apple tested and recommended. Not all bridge chipsets are equally compatible with a given hardware and driver configuration.
 
Last edited:

Nuke61

macrumors 6502
Jan 18, 2013
325
0
Columbia, SC
But it works fine on Mac Pro
But it doesn't work fine on your newMac. Does the built-in SD card reader work well? If it does, you could use that while you're working on a solution with the Delkin. But i still say contact Delkin and see if they have a firmware update.

There's a reviewer on Amazon who said this reader was super slow on his Mac, like USB 1.0 speed. http://www.amazon.com/Delkin-Universal-Memory-Card-Reader/product-reviews/B004WEPDK2/ref=cm_cr_dp_qt_hist_one?ie=UTF8&filterBy=addOneStar&showViewpoints=0
 

Raima

macrumors 6502
Jan 21, 2010
397
7
Can you also confirm you're using a USB3 cable to connect the device to the iMac?

You can generally tell a USB3 cable by the blue connections. USB3 cable has more wire channels internally than a USB2 cable.

Using a USB2 cable to connect to a USB3 device may create undesired results.
 

iamgalactic

macrumors regular
Apr 21, 2010
180
58
plug in the card reader and do this:

go to apple>about this mac>system report>USB

is your card reader under the USB 3.0 section?
 

PJM82

macrumors member
Apr 28, 2013
74
0
United Kingdom
So older generation is better?
In some cases yes. The chipsets are different so will have different quirks and the drivers will differ. Its almost like running Windows now. On one of my PCs my USB 3.0 stick works just fine, on the other it doesn't. Same version of Windows, similar hardware specs.

But it doesn't work fine on your newMac. Does the built-in SD card reader work well? If it does, you could use that while you're working on a solution with the Delkin. But i still say contact Delkin and see if they have a firmware update.
This is worth a try. If its not possible or still doesn't work then USB 3.0 card readers aren't that expensive, I would consider trying another one. Any other USB 3.0 devices you can try?