I use
MSI Afterburner (can work with any other GPU brands). You can have the graphs (in realtime) of specific data you want to show on a window and/or you can have an On-Screen Display numerics of such data shown to you as an overlay while gaming. You can select which specific data (FPS, GPU Temp, CPU Temp, GPU Usage, CPU Usage, RAM Usage, and many many more) that you only want to show.