When you install a Plug and Play device, Windows automatically configures the device so it will work properly with the other devices that are installed on your computer. As part of that configuration process, Windows assigns a unique set of system resources to the device you are installing. These resources can include one or more of the following:

  • Interrupt request (IRQ) line numbers

  • Direct memory access (DMA) channels

  • Input/output (I/O) port addresses

  • Memory address ranges

For definitions of each of these terms, see the Device Management Glossary.

Each resource that is assigned to your device must be unique or else the device cannot function properly. For Plug and Play devices, Windows automatically configures these resources properly. However, you can manually configure devices by using Device Manager.

Generally, avoid changing resource settings manually, because when you do, the settings become fixed, and Windows will then have less flexibility when allocating resources to other devices. If too many resources become fixed, Windows may not be able to install new Plug and Play devices.

Occasionally, two devices require the same resources, resulting in a device conflict. If this occurs, you can manually change the resource settings to be sure each setting is unique. However some resources, such as interrupts on PCI devices, can be shared, depending on the drivers and computer.

Depending on the type of device you are installing, you might have to manually configure these settings. When you install a non-Plug and Play device, Windows cannot automatically configure the resource settings for the device. For instructions, see the manual that came with your device.


Changing resource settings improperly can disable your hardware and cause your computer to malfunction or become inoperable. Change resource settings only if you are certain that the new settings do not conflict with other hardware, or if a hardware manufacturer has provided specific resource settings for a device.