Before trying to identify an unknown ACPI device, let’s go over some of the troubleshooting basics. Have you ever experienced device driver problems on your computer and tried to manually fix or fix them? If yes, you may be familiar with the identification (ID) of hardware devices, such as vendor and device ID. In case you have never seen such IDs, you can take a look 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 on “My Computer” in XP or “Computer” in Windows 7 and Vista.
3. Click “Manage”
4. Choose “Device Manager” from the list of items on the left side of the window
5. Here you can choose and expand the hardware devices to display additional components. Let’s 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 on “Properties”
   3. Click on the “Details” tab
   4. Find the “Device Instance ID” in XP or “Device Instance Path” in Windows 7 and Vista in the drop-down list provided. You will be provided with alphanumeric data, and this data includes the hardware IDs of your USB bus controllers. DEV_xxxx and VID_xxxx stand for Device ID and Vendor ID, and the preceding string of letters or numbers (xxxx) is their value.

Device and vendor IDs are important pieces of information that you need to find additional information about 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 does not provide you with these IDs, but instead provides you with a series of strings such as: ACPI | PNP0100 | 4 & E0550D1 & 1 or ACPI “| ATK0110 | 1010110?

Now you know that this is an ACPI device and some questions that may arise are: What is ACPI? How can I find ACPI device drivers using device IDs? And how can the ACPI unknown device problem be solved?

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

In case the installation CD is not available or if after using the CD your Unknown ACPI Device remains on your computer, you can try searching online and downloading them manually. There is still useful data that you can use to find your device drivers online, using our examples: ACPI| PNP0100 |4 and E0550D1 and 1 and ACPI| ATK0110| 1010110. The highlighted part of the first example represents the PNP (Plug and Play) device ID with the value 0100. You can now search online for your ACPI unknown device driver by typing ACPI | PNP 0100. The same happens with the second example; you can search using ATK0110. Typing this data into the search engine will give you thousands of results and can cause headaches and frustrations searching online. Make a note to download your device drivers only from the official and reputable manufacturer’s website to avoid additional issues besides Unknown ACPI Device such as computer viruses and malware.