10 Replies Latest reply: Feb 7, 2014 7:51 AM by F.Lateralis
dandig Level 1 Level 1 (15 points)

I have a new iMac and weird things have happened with the USB3 ports since day one.  At the moment I have a USpeed 4-port USB3 hub and when the iMac starts up, the hub goes onto the USB2 bus, not USB3.  To get it to show up on the USB3 bus you have to pull the power from the hub and plug it back in again.  It has to be the power , simply pulling the USB plug and putting that back in does not work.


At first it sounds like a bad hub , but the exact same thing was happening with another set of things plugged in before I even got the hub.  When I first started up the computer I plugged in an older wired USB Apple keyboard ( the one that has a USB hub built into it) and that seemed to cause ALL other USB devices which were plugged directly into the iMac ( not into the hub of course) to go onto the USB2 bus and not the USB 3 one.


There has to be a link between these two problems.... but they are both slightly different.

iMac, OS X Mountain Lion (10.8.2), 27" 3.4GhZ
  • 1. Re: new 27" iMac, USB3 troubles
    dandig Level 1 Level 1 (15 points)

    After restarting and shutting down the iMac about 50 times with various combinations of things plugged into it I have got some further details...


    It seems that the the third USB port from the left it the culprit here.  With the hub plugged into that port, upon shutting down the computer and re-starting it , it comes up on the USB2 bus.  This ONLY happens on that particular USB port.  And it ONLY happens during a complete shutdown, not a re-start.


    I've tried some other USB3 things in the same port and they seem to work ok.  At the moment I can't replicate the issue with any other products that I have so I'm thinking that this has to be related to the use of a hub in that port ?  It can't be specific to this one hub that I'm using since that wouldn't know which of the four iMac ports it was plugged in to.


    Does anyone else out there have a late 2012 iMac and a USB3 hub of some sort that they can test this with ?


    .... still working on narrowing down the issues I had when the USB keyboard was plugged in becasue that one cause all other devices to drop down to USB2

  • 2. Re: new 27" iMac, USB3 troubles
    Baby Boomer (USofA) Level 9 Level 9 (55,575 points)

    Call AppleCare ASAP!!!!!!!


    You should not be troubleshooting a spanking brand new out of the box computer.


    Take full advantage of your warranty. You have 14 days from the date of purchase to exchange and/or return with no questions asked!


    You also have 90 days of FREE phone tech support.




































  • 3. Re: new 27" iMac, USB3 troubles
    dandig Level 1 Level 1 (15 points)

    Thanks.... Apple are looking into this already.  I just wandered if anyone else had experienced any similar issues or whether anyone has a USB3 hub and a new iMac that they can try and replicate the same issue.  It's such a weird issue that it has me wandering whether it's not a bug with with the iMac in general and not just my one , in which case simply getting a replacement wouldn't help me and would be a waste of time.

  • 4. Re: new 27" iMac, USB3 troubles
    Chessie 01 Level 1 Level 1 (85 points)

    In addition, I recommend that you purchase Apple Care.  You can do so during the 1 year warranty period.  It offers you 3 years of free phone tech support and it extends your basic warranty. 

  • 5. Re: new 27" iMac, USB3 troubles
    dandig Level 1 Level 1 (15 points)

    Thanks, I already have AppleCare

  • 6. Re: new 27" iMac, USB3 troubles
    LownoteNB Level 1 Level 1 (0 points)

    This is slightly off topic but I'm scheduled to get my new iMac on Feb 5, and I have most of what I need in hand to make a quick transition from a 3-year old iMac.  I would appreciate knowing about your experience.  My ancient Belkin USB 2 hub is starting to get flakey and I thought I would purchase a new USB 3 hub to replace it.  However, I'm seeing warnings that wireless devices like my MagicPad may not work with the USpeed USB 3 hub that you own. Have you had any problems with your wireless devices when the hub is in operation or devices working at USB 3 speed when plugged into your hub?  In addition to some older USB devices that I want to plug into the new hub (Epson printer, Focusrite audio interface, Mac extended keyboard, video card reader), I would also like to plug in a powered 3TB Seagate USB 3 external HD that I'm going to use as a TM backup. Main data storage will be on new Thunderbolt Drobo. Thanks. 

  • 7. Re: new 27" iMac, USB3 troubles
    dandig Level 1 Level 1 (15 points)

    That's interesting... where are you seeing these warnings ?


    I haven't had any problem with wirless devices.  Im using the keyboard and the magic trackpad without issue.


    Obviously though if you've read this thread you will see that I have had some issues with things coming in at USB2 speed on this hub.... though ONLY when it's attached to one specific USB port out of the four of them.


    I'd love to know where you read about other issues.... ?

  • 8. Re: new 27" iMac, USB3 troubles
    LownoteNB Level 1 Level 1 (0 points)

    The comments came from several Amazon hub listings--both the product descriptions and the user reviews, some of which appear to be written by tech-savvy users.  Evidently the chipset in your hub is used by several manufacturers.  Here dips one review that saw.     http://www.amazon.co.uk/Plugable-Power-Adapter-Mains-Chipset/dp/B009EX24T4/ref=s r_1_1?s=computers&ie=UTF8&qid=1359498581&sr=1-1


    Here is another review that caused me to write to you


    http://www.amazon.co.uk/Chipset-Uspeed-Adapter-Backward-Compatible/dp/B007ZW1TYW /ref=sr_1_fkmr0_2?s=computers&ie=UTF8&qid=1359499111&sr=1-2-fkmr0

  • 9. Re: new 27" iMac, USB3 troubles
    William Donelson Level 4 Level 4 (2,495 points)

    USB3 radiates the same frequencies used by WiFi and many wireless products.


    In my experience, not a single USB3 hub is reliable due to stupidity of USB3 design.


    AVOID USB3 and if you must use it, use short BEST QUALITY cables, heavily shielded. USB3 has caused repeated trouble in our offices.

  • 10. Re: new 27" iMac, USB3 troubles
    F.Lateralis Level 1 Level 1 (0 points)

    Does anybody has a solution yet?


    It looks I have the same problem on my iMac 27"",  just bought.

    - Cannot format (with disk utility) a USB 3 external harddisk (WD red 2TB harddisk in a USB 3 case), connected to the USB 3 port, however could format via the Apple-keyboard (USB 2) that is connected to USB3.

    - Looses connection while performing a backup (using backup tool  Synchronise) connected on USB3. While USB 2 no problem, but terrible slow.


    However, I don't have any connectionproblems with my "WD MyBook 4 TB harddrive", which was pre-formatted by WD.