Level 4
Do you want a resource friendly program to keep an eye on your computer's hardware? You should give Sidebar Diagnostics a try.

It is a free and open source application. When you install the program, it adds a side-bar to the right side of the screen that displays data from five core hardware monitoring tools: CPU, RAM, GPU, Drives and Network.

The sidebar display ensures that the readings are available at all times on the desktop. If you prefer a standalone program with its own window, check out alternatives such as HwInfo, Windows Resource Monitor, or SpeedFan (for controlling temperatures).