I recently got a OWC Thunderbolt 2 Dock and am hooking my monitors into it. I have Display Port to MiniDisplay Port going from the monitor to the dock, one thunderbolt cable going from dock to Macbook Pro, and one Display Port to MiniDisplay Port going from a second monitor to the MBP.

Every so often, the monitor hooked into the dock will simply 'reset' or disconnect and then connect again. Everything I had on that monitor moves to my laptop main display and then the monitor appears again.

I have checked the lights/connections and there is no poweroff of the dock. Has anyone else experierenced this or know of a solution?

UPDATE: After switching ports with monitors, the same thing happens with the second monitor in the Dock. It also happens with HDMI to the dock (which is why I went with DisplayPort -> miniDisplayPort in the first place).

  • I don't have that dock, but you might look into seeing if this is a known defect that OWC might fix or replace for. Also, does this happen with the HDMI port (if your monitor has an HDMI port) and does it happen with both monitors? (What happens when you switch the monitors? Doe the one connected to the dock still reset occasionally?)
    – Cajunluke
    Nov 11, 2015 at 14:42
  • I have the same problem. But when i switch over to wifi everything goes well, the dock remains active like it should. So i think that network hiccups on the ethernet port causes the tb2 dock to restart.
    – user180428
    Apr 20, 2016 at 13:04
  • I have the same issue with 30" Cinema and lot of HDD connected to the dock. I am using macbook pro retina with two thunderbolt ports so after switching the big monitor to the second port directly on the mac the monitor is not reseting itself. The external HDD still does though and that one goes directly thru the dock :( May 17, 2016 at 9:27
  • After two years of the madness, I’m glad to see I’m not going crazy. I have my audio interface connected to the owc thunderbolt 2 dock and have intermittent problems as well.
    – Maj Jam
    Apr 15, 2018 at 2:46

7 Answers 7


January 22, 2016: I had similar problem (intermittent monitor and hard disk disconnects) and called the OWC HelpDesk. The OWC technician said that problem was with the Mac Thunderbolt driver, not the Dock, and the solution is to reset PRAM/NVRAM: https://support.apple.com/en-us/HT204063 Since PRAM/NVRAM reset, the intermittent screen and disk resets have stopped. I am keeping fingers crossed.

January 30, 2016: The monitor/disk disconnects have restarted :-(

February 9, 2016: Has worked flawlessly for past 10 days, following another NVRAM reset. I wish I could understand the problem a little better, what causes it in the first place and why it goes away after NVRAM reset?


I have the OWC Thunderbolt 2 dock and used it for more than a year with a 2011 MacBook Pro, Thunderbolt Display, and HP monitor with no problems. I connected the Thunderbolt Display to my MacBook Pro, then connected the dock to the Thunderbolt Display with a Thunderbolt cable. The HP monitor was connected to the Thunderbolt Dock via HDMI. This setup allowed me to use both external displays as well as my MacBook Pro's display.

I recently replaced the MacBook Pro with a 2011 iMac 21.5. Hooked everything up the same way -- iMac to the Thunderbolt Display, Thunderbolt Display to the Dock, HDMI from Dock to the HP Monitor. Everything works, at least for a few minutes, then the HP monitor goes dark and I all the disks connected to the Dock disconnect. Sometimes they immediately reconnect then disconnect so that the notifications cannot keep up.

I've tried the NVRAM reset to see if that remedies the problem. What I've discovered, though, is that disconnecting the HDMI cable connecting the HP monitor and taking it out of the loop allows everything to work perfectly. No intermittent disk and Thunderbolt disconnects). I'm at a loss. I don't necessarily need three screens but it would be cool. I'm not understanding why the setup worked with the MacBook Pro but not the iMac.


I have a theory that the OWC TB2 dock is periodically being power cycled. I don't know if this is due to a faulty power supply, but mine is behaving this way. Everything connected to it quickly disconnects and reconnects, which leads me to this theory.


This is what the manual says regarding displays :

"If you are connecting only one display to the dock, you can do so via the following connection types: Thunderbolt, Mini Displayport, HDMI. HOWEVER, if you intend to connect two displays simultaneously, you MUST use BOTH a native Thunderbolt display and a native HDMI display. Other combinations or adapters will not work."

I connected the dock to an iMac 5K running 10.11.1, and within 30 seconds...kernel panic. Prior to connecting the dock, the OS had an issue with USB3.

The latest update 10.11.4 fixed this issue :
"• Fixes an issue that caused USB audio devices to disconnect."

So, after updating the OS and switching the docks' power supply, it's finally playing nice.

The power supply I'm using is from a Lacie hard drive, 12v 1.5a The power supply that came with the dock is 12v 6.0a. Perhaps the 6.0a is causing the dock to reset.

Hope this helps.

  • The amperage rating on a power supply is not what it's pushing, but the maximum the load will be able to draw. Switching out a 6A for a 1.5A will limit the number of peripherals you can attach to the dock and may cause you to damage the power supply and/or the dock. In the case you described above, your power supply has nothing to do with the issue.
    – Allan
    Apr 20, 2016 at 13:37
  • @Allan if the power supply had a defect, switching to the other power supply might've cleared up an issue. not that it's a good solution if the dock is expecting to be able to draw up to six amps. but i wouldn't rule out a bad power supply.
    – worc
    Oct 5, 2016 at 20:58

Try moving the wifi router away from the dock as possible. Your cell phone near to the dock during a call can also cause breakage. These two simple solutions enable me to work without nerves for the past 2 months.


I gave up on it some time ago, but recently had to move to USB drive for Time Machine and put it back on. It seems that the issue is only when both 30" Cinema display and USB drive are connected. If I take the display out and unplug it from the current the drives work ok. I should have tested it for longer period of time but so far I use both in the following sequence: MacBook Pro Tunderbolt-OWC dock-then USB 3 and 30" cinema are connected to the dock.

It does not make any difference in my case if the monitor is plugged directly to my laptop or not.


I had the same issues you have. It turned out the Ambrosia audio support driver for Snapz Pro X was causing the system to throw away the dock at times. After removing it it's been good for a week now.

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