The safest and most reliable source for the is the official Asus support website. Even though the P8Z77-V LX is a discontinued model, Asus still hosts legacy drivers.
The Asus P8Z77-V LX PCI Simple Communications Controller Driver is a software component designed to facilitate communication between your motherboard's PCI Simple Communications Controller and your operating system. The PCI Simple Communications Controller is a hardware device that enables communication between your computer and various peripherals, such as modems, sound cards, and network cards. Asus P8z77-v Lx Pci Simple Communications Controller Driver