Before trying to identify Unknown ACPI Device, let us review some of the troubleshooting basics. Have you ever experienced device driver problems on your computer and tried to troubleshoot or fix them manually? If yes, you might be familiar with Identification (ID) of hardware devices such as the Vendor and Device ID. In case you have never seen such IDs, you may take a glance by opening your Device Manager. There are several ways to open your Device Manager in Windows, and you can follow the procedures below:

  1. Click “Start” in XP or “Windows Button” in Windows 7 and Vista
  2. Right-click “My Computer” in XP or “Computer” in Windows 7 and Vista
  3. Click “Manage”
  4. Choose “Device Manager” on the list of items in the left side of the window
  5. Here you can choose and expand the hardware devices to display additional components. Let us choose the “Universal Bus Controllers” as an example:
    1. Right click on one of its components such as “Universal Host Controller” or “Root Hub”
    2. Click “Properties”
    3. Click “Details” tab
    4. Search for the “Device Instance ID” in XP or “Device Instance Path” in Windows 7 and Vista from the provided drop-down list. Alphanumeric data will be provided to you, and these data include the hardware IDs of your USB Bus Controllers. The DEV_xxxx and VID_xxxx stand for Device ID and Vendor ID, and the string of letters or numbers (xxxx) preceding them is their value.

Device and Vendor IDs are important data you need to search for additional information regarding your hardware device drivers, especially when you have an “Unknown Device” listed under “Other Devices” in your Device Manager. What if the Device Instance ID/Path will not provide you with these IDs, instead it will provide you with series of strings such as: ACPI|PNP0100|4&E0550D1&1 or ACPI”|ATK0110|1010110?

Now, you know that you are dealing with an ACPI device and some questions that may arise are: What is ACPI? How can you search for the ACPI device drivers using device IDs? And how can you solve ACPI Unknown Device problem?

ACPI stands for Advanced Configuration and Power Interface; it is an open industry specification that provides an open standard for computer power management and operating system-centric device configuration. This specification is co-developed by Microsoft, Intel, Toshiba, Phoenix, and Hewlett-Packard; it enables independent growth or development of power management technologies while ensuring that they continue to support and function together. ACPI hardware device drivers are mostly included in the built-in device drivers on your computer or you may obtain them from the installation CD of your mother board.

In case the installation CD is not available or, if after using the CD, your Unknown ACPI Device remains on your computer, you may try searching online and downloading them manually. There are still useful data that you may use to search for your device drivers online, using our examples: ACPI|PNP0100|4&E0550D1&1 and ACPI|ATK0110|1010110. The highlighted portion of the first example stands for PNP (Plug and Play) Device ID with the value of 0100. Now you can search online for your ACPI Unknown Device driver by typing ACPI|PNP 0100. It is the same with the second example;you can search using ATK0110. Typing these data on the search engine will give you thousands of results, and may give you headaches and frustrations from searching online. Take note to download your device drivers only from reputable and official manufacturers’ website to avoid additional troubles, aside from Unknown ACPI Device, such as computer viruses and malware.