How to Fix ACPI/SMO8800 Unknown Device in Dell PC Laptops

Problematic devices listed and labelled as ‘Unknown Device’ in the Device Manager have been a troublesome issue for Dell PC users. One of these problematic devices commonly encountered on Dell PC models is the hardware device with a device ID property value: ACPI/SMO8800. This report will quickly discuss how to fix this hardware device problem, including an actual example of downloading the device driver from the official website of Dell to get rid of this Unknown Device in the Device Manager.

You can easily fix the Unknown Device with device ID ACPI/SMO8800 by downloading and installing the device driver for your Dell PC model available in the official website of Dell. According to Dell, the hardware device ID ‘ACPI/SMO8800′ belongs to ST Micro Free Fall Sensor. This device monitors the acceleration of the hard drive, can detect rapid changes in physical position, and is able to secure sensitive parts inside the hard drive that can be damaged or lost due to sudden drops.

On the other hand, you must first check if the Unknown Device listed in the Device Manager is indeed the Free Fall Sensor of your Dell PC. You can do this by making sure that the Hardware Ids Value of your Unknown Device is ACPI/SMO8800 (see the screenshot below), otherwise you can follow the detailed information provided at to identify your Unknown Device.

a) Unknown Device Properties

Unknown Device Free Fall Sensor

After ensuring that the Unknown Device of your Dell PC is the Free Fall Sensor, you can now visit the official website of Dell at and search for the required device driver.

Let us take the Dell Precision M4500 as an example.

  1. In the official website of Dell, you must first click the link ‘Drivers & Downloads’ at the bottom of the homepage
  2. Then click one of the green buttons labelled as ‘Drivers & Downloads Home’.
  3. Select the option to ‘Choose from a list of all Dell products’, and then click Continue.

b) Options in Looking for Dell PC model

Unknown Device ACPI/SMO8800 2

4. In the next page, you will need to select the Product Type which is ‘Laptops’.

c) Selection of Dell Products

Unknown Device ACPI/SMO8800 3

5. Choose your Dell Laptop, and then select PC model. Our example is one of the Precision Mobile Work Station, and its specific model is Precision M4500.

d) Specifying Dell PC Model

Unknown Device ACPI/SMO0080

6. In the next page, you must select the Operating System of your Dell PC, expand the ‘Application’ category, look for the device driver file for Free Fall Sensor, and then click the ‘Download File’ button.

e) List of Dell Device Drivers

Unknown Device ACPI/SMO8800

7. After downloading the device driver for Free Fall Sensor, you must run the driver executable file, reboot your Dell PC, and make sure that there are no more problematic device or Unknown Device listed in the Device Manager.

However, there are also cases where there are more than one Unknown Device or problematic device, marked by a warning yellow symbol (! or ?), listed in the Device Manager. Solving these issues will require a lot of time and energy, and to make sure that you will have the correct device drivers for these problematic devices, you can consider using Driver Detective software. Driver Detective will keep all the device drivers required by your PC up-to-date and will also aid you in fixing easily problems caused by device driver corruptions, failures, and accidental erasures. Click here to learn more about this option.