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OWC miniStack STX

Support Manual

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1.1 System Requirements

Operating System

  • Mac: macOS 10.14 or later
  • PC: Windows 10 or later
  • Other: Linux, iPadOS 13 and later, ChromeOS (latest version recommended), Android (latest version recommended)


  • Works with any Mac, PC, or tablet with a Thunderbolt (USB-C) port

Supported Drives

  • 3.5"/2.5" SATA HDDs/SSDs
  • NVMe M.2 SSD with a M-key connector and 2280 form factor

1.2 Package Contents

1.3 About This Manual

The images and descriptions may vary slightly between this manual and the unit shipped. Functions and features may change depending on the firmware version. The latest product details and warranty information can be found on the product web page. OWC’s Limited Warranty is not transferable and

General Use Precautions

  • Read this user guide carefully and follow all recommended usage steps and precautions.
  • To avoid damage, do not expose the device to temperatures outside the following ranges:
    • Environmental (Operating)
      • Temperature (ºF): 41º — 95º
      • Temperature (ºC): 5º — 35º
    • Environmental (Non-Operating)
      • Temperature (ºF): -4º — 140º
      • Temperature (ºC): -20º — 60º
  • Always unplug the device from the electrical outlet if there is a risk of lightning or if it will be unused for an extended period of time. Otherwise, there is an increased risk of electrical shock, short-circuiting or fire.
  • Do not use the device near other electrical appliances such as televisions, radios or speakers. Doing so may cause interference which will adversely affect the operation of the other products.
  • Protect your device from excessive exposure to dust during use or storage. Dust can build up inside the device, increasing the risk of damage or malfunction.
  • Do not block any ventilation openings on the device. These help to keep the device cool during operation. Blocking the ventilation openings may cause damage to the device and cause an increased risk of short circuiting or fire.

Safety Precautions

  • Read this user guide carefully and follow the recommended steps for assembly.
  • Use proper anti-static precautions while installing drives into this enclosure. Failure to do so can cause damage to your drive mechanisms and/or the enclosure.
  • Do not attempt to disassemble or modify the device. To avoid any risk of electrical shock, fire, short-circuiting or dangerous emissions, never insert any metallic object into the device. If it appears to be malfunctioning, please contact technical support.
  • Never expose your device to rain, or use it near water or in damp or wet conditions. Never place objects containing liquids on the drive, as they may spill into its openings. Doing so increases the risk of electrical shock, short-circuiting, fire or personal injury.

1.4 Overview

A. (1) SATA drive bay activity LED - Power & Data Connection = Solid Green / Drive Activity = Flashing Green

B. (1) NVMe drive bay activity LED - Power & Data Connection = Solid Green / Drive Activity = Flashing Green

C. (3) Thunderbolt 4 ports - Connect Thunderbolt devices.

D. (1) Thunderbolt 4 host port - Connect a compatible host.

E. (1) Power Port - Connect the power cable to power the device

F. (1) Kensington Security slotAttach a Kensington Security lock.

    Getting Started

    2.1 Device Setup

    1. Connect the included Thunderbolt 4 cable into the Thunderbolt 4 Host Port on the back of the OWC miniStack STX. Connect the other end of the cable into a compatible host.

    2. The OWC miniStack STX comes pre-loaded with a formatting utility called OWC Drive Guide. Once the OWC miniStack STX is connected, the drive will mount on the operating system and display a folder "OWC SETUP".
    NOTE: Please skip the following steps if a different formatting method is desired.

    4. Open "OWC SETUP" and double-click the OWC Drive Guide utility. Follow the instructions to complete the formatting process.

    5. Additional information regarding OWC Drive Guide can be found in the Support Manual.

    2.2 Assembly Steps

    This section describes the process of installing SATA and NVMe drives into the OWC miniStack STX.
    NOTE: An installation video is available by visiting the Support Guide page for the OWC miniStack STX (

    Opening the miniStack STX

    1. Place the miniStack STX upside-down and remove the four screws on the bottom side of the outer case.

    2. While gripping the miniStack place it right-side up with the OWC logo facing forward. Slowly life the top case off from back to front.
    NOTE: There is a cable clipped inside to the outer case and connected near the NVMe M.2 SSD circuit board. Opening slowly helps prevent accidentally disconnecting the cable.

    3. Carefully remove the cable from the routing clip. Then carefully disconnect the cable by pulling on the cable connector near the NVMe M.2 SSD circuit board. Please do not directly pull on the cable.

    Drive Installation

    3.5-Inch Drive Installation

    1. Place the 3.5-Inch drive into the chassis and connect into the SATA connector on the circuit board. Make sure the drive is fully seated.
    2. Secure the drive from the inside using the included HDD Mounting Screws.
    3. Turn over the miniStack and further secure the drive using the HDD Mounting Screws.

    2.5-Inch Drive Installation

    1. Place the 2.5-Inch drive into the chassis and connect into the SATA connector on the circuit board. Make sure the drive is fully seated.
    2. Turn over the miniStack and further secure the drive using the SSD Mounting Screws.

    NVMe Drive Installation

    1. Remove the NVMe M.2 SSD mounting screw and insert a NVMe M.2 SSD fully into the connector at a slight angle.
    2. Press the NVMe M.2 SSD down so the drive’s notch fits around the mounting post.
    3. Secure the drive by using the NVMe M.2 SSD mounting screw that was first removed.

    Closing the miniStack STX

    1. Carefully place the cable back into the cable routing clip. Then carefully connect the cable back into the connection near the NVMe M.2 SSD circuit board.

    2. Place the top case back on the miniStack from front to back and while gripping, flip the unit upside down. Secure the miniStack by using the four removed case screws.

    3. The installed drives are ready to be formatted. Please visit for formatting options.

    Device Management

    3.1 Unmounting Options

    To ensure no data is lost during normal use, always eject or unmount the OWC miniStack STX from your operating system before disconnecting the device. Unmounting options are provided below.

    OWC Dock Ejector

    This application safely ejects all drives connected to a Mac system with a single click. To install this application, please follow the steps below:

    1. Download the installer file for Mac:
    2. Launch the installer and follow the prompts. No restart is required.
    3. Once the app is running an icon like the one shown below will appear in the macOS menubar. Clicking on the icon will provide options to unmount the OWC miniStack STX.
    4. Full user manual can be viewed by visiting

    Manually Unmounting Drives


    1. Drag the icon for the disk you wish to unmount to the trash can; OR
    2. Right-click the disk icon on the desktop, then click “Eject”; OR
    3. Highlight the disk on your Desktop and press Command-E.


    1. Go to the System Tray (located in the lower right corner of your screen). Click on the “Eject” icon (a small green arrow over a hardware image).
    2. A message will appear, detailing the devices that the “Eject” icon controls, i.e., “Safely remove...” Click on this prompt.
    3. You will then see a message that says, “Safe to Remove Hardware.” It is now safe to disconnect the Mercury Elite Pro Dock from the computer.
      1. The steps above are applicable to Windows 10 build 1803 and earlier. If you are using Windows 10 build 1809 (October 2018) or later, you can eject the drive by clicking the ‘Show hidden items’ menu in the Taskbar, then clicking ‘Safely Remove Hardware and Eject Media’, and last select the ‘Eject’ option for this volume.

    3.2 Usage Notes

    • Thunderbolt 4 devices like miniStack STX are not supported for use with legacy Thunderbolt 1 and 2 machines via Apple's Thunderbolt adapter. Use with a Mac, PC, or device equipped with USB-A only requires a USB-C to USB-A adapter cable (available separately). Up to two external displays supported by Intel Mac machines over Thunderbolt connection. Apple silicon M1 and M2 Macs support one external display over Thunderbolt.
    • Use of miniStack STX with a USB-C or USB-A host allows use of the miniStack STX’s SATA drive only and use of its ports for USB accessories only.
    • Some internal drives may not support LED status function.
    • UltraStudio Recorder 3G is not compatible. System Report will show the device being connected; however, the driver won’t load which doesn’t allow for use of the device. UltraStudio Recorder 3G works properly when directly connected to a system.

    Support Resources

    4.1 Troubleshooting

    • Begin troubleshooting by verifying that the power cable is connected to the miniStack STX and to a power source. If the power cable is connected to a power strip, make sure that the power switch on the strip is turned on.
    • Verify that the Thunderbolt 4 cable is properly plugged into the computer and the host port on the miniStack STX. If the miniStack STX is still not working properly, try connecting to another computer or using another Thunderbolt 4 cable.
    • If issues continue to occur, please know that OWC support is here to help. Contacting support information can be found in Section 4.4. Please have your serial number ready which is located on the bottom of the OWC miniStack STX and printed on the original packaging.

    4.2 Online Resources

    4.3 About Data Backup

    To ensure that your files are protected and to prevent data loss, we strongly suggest that you keep two copies of your data: one copy on your OWC Envoy Pro 1A and a second copy on either your internal drive or another storage medium, such as an optical backup, or on another external storage unit. Any data loss or corruption while using the OWC Envoy Pro 1A is the sole responsibility of the user, and under no circumstances may OWC, its parents, partners, affiliates, officers, employees, or agents be held liable for loss of the use of data including compensation of any kind or recovery of the data.

    4.4 Contacting Support

    Terms & Conditions of Sale


    OWC’s products are subject to OWC’s Terms & Conditions of Sale located at Terms of Sale or other applicable terms. The OWC miniStack STX comes with a 1-Year Limited Warranty. Additional warranty information can be viewed by visiting Hardware Warranties.


    The material in this document is for information purposes only and subject to change without notice. While reasonable efforts have been made in the preparation of this document to assure its accuracy, OWC, its parent, partners, affiliates, officers, employees, and agents assume no liability resulting from errors or omissions in this document, or from the use of the information contained herein. OWC reserves the right to make changes or revisions in the product design or the product manual without reservation and without obligation to notify any person of such revisions and changes.

    FCC Statement

    Warning! Modifications not authorized by the manufacturer may void the user’s authority to operate this device.
    NOTE: This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generates, uses and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference to radio communications. However, there is no guarantee that interference will not occur in a particular installation. If this equipment does cause harmful interference with radio or television reception, which can be determined by turning the equipment off and on, the user is encouraged to try to correct the interference by one or more of the following measures:

    • Reorient or relocate the receiving antenna.
    • Increase the separation between the equipment and receiver.
    • Connect the equipment to an outlet on a circuit different from that to which the receiver is connected.

    Copyrights and Trademarks

    No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written consent of OWC.

    © 2023 Other World Computing, Inc. All rights reserved. Envoy, OWC and the OWC logo are trademarks of New Concepts Development Corporation, registered in the U.S. and/or other countries. Mac and macOS are trademarks of Apple Inc., registered in the U.S. and other countries. Thunderbolt and the Thunderbolt logo are trademarks of Intel Corporation in the U.S. and/or other countries. Other marks may be the trademark or registered trademark property of their owners.

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