Total Network Inventory: Professional PC audit and network inventory management software - fits best for a for companies of all sizes. Free for 60 days.
Open Hardware Monitor - Monitors temperature sensors, fan speeds, voltages, load and clock speeds, with optional graph.
Network Inventory Advisor - Network Inventory Advisor audits all network software and hardware simply and efficiently
Guru3D - Guru of 3D: PC Hardware Reviews and tests
Lansweeper - Lansweeper discovers Windows, Linux and Mac machines in your network.
Geforce Experience - GeForce Experience is a new application from NVIDIA that optimizes your PC in two key ways.
Nmap - Nmap Free Security Scanner, Port Scanner, & Network Exploration Tool. Download open source software for Linux, Windows, UNIX, FreeBSD, etc.