MSI Afterburner - Tool to manage video cards. Shows video card stats (temp, GPU usage, etc.).
Open Hardware Monitor - Monitors temperature sensors, fan speeds, voltages, load and clock speeds, with optional graph.
NVIDIA Inspector - Nvidia Inspector is a small and handy tool that displays hardware information for Nvidia-based...
CapFrameX - Frametime capture and analysis tool based on Intel's PresentMon. Overlay provided by Rivatuner Statistics Server.
Guru3D - Guru of 3D: PC Hardware Reviews and tests
OCAT - Open Capture and Analytics Tool. If you want to know how well a game is performing on your machine in real-time with low overhead. It supports all major APIs on Windows – Direct3D® 11, 12 and Vulkan® – and can show an in-game overlay