The Intel(R) 82801FBFBM PCI Express Root Port - 2666 is a hardware component related to the Intel ICH6 (Intel 82801FB) chipset family, which was used in older Intel-based motherboards, typically around the time of Intel's Pentium 4 and early Core 2 Duo processors. The PCI Express Root Port is part of the system's PCIe (Peripheral Component Interconnect Express) architecture, which handles communication between the CPU, RAM, and various expansion cards (such as graphics cards, network adapters, etc.).

The "2666" in the name refers to the PCIe bus speed, which in this case operates at a 2.66 GHz speed (a common speed associated with older systems and chipsets). The driver is the software that allows Windows to interact with the chipset and its components, including PCIe devices.