The Hardware Compatibility List (HCL) is a list that indicates hardware components that are compatible with a specific software or operating system. If software installation fails due to incompliance with the HCL, it's most likely due to core hardware components like the Network Interface Card (NIC) or the Central Processing Unit (CPU) not being supported or not meeting the software's minimum hardware requirements. The PSU, KVM, RAM, and DVI are less likely to directly impact software compatibility as defined by the HCL.