Typically, the computer BIOS configures a limited bus-number range for PCI Express bridge devices. This issue may occur if the operating system runs out of Peripheral Component Interconnect (PCI) bus numbers. In this situation, a Code 12 error is generated. Therefore, any PCI Express bridge device that requires resources from the bridge resource window will fail enumeration. Additionally, no bridge resource window requirements for the PCI Express bridge device are generated. This behavior is interpreted as an indication that the bridge resource window is disabled. By default, when you start or reset PCI Express bridge devices, the initial values of the limit register for the bridge resource window are less than the initial values of the base register for the bridge resource window. This issue may occur because of the initial state of the PCI Express bridge device in the expansion chassis. The device is not working properly because Windows cannot load the drivers required for this device. This device cannot find enough free resources that it can use. Additionally, you may receive one of the following error messages when you view the device properties in Device Manager: In this scenario, the devices may not be enumerated correctly, or they may not start correctly. There are devices connected to the PCI Express expansion chassis.A PCI Express expansion chassis is connected to a computer.For more information about how to back up, restore, and modify the registry, click the following article number to view the article in the Microsoft Knowledge Base: 322756 How to back up and restore the registry in Windows Symptoms Make sure that you know how to restore the registry if a problem occurs. Make sure that you back up the registry before you modify it. This article contains information about how to modify the registry.

Pci express drivers for windows 10