In All-In-One mode, the LED represents system memory and CPU usage as well. Hovering your mouse over the LED gives a real-time numerical reading of the read and write performances in megabytes. It comes with some aesthetic pleasantries that let you customize transparency and colors of the onscreen LED lights.
As a nice feature, you can have your Scroll Lock key or the system-tray icon flash every time read or write activity occurs. We recommend HddLed to anyone seeking an easy-to-use monitoring tool that doesn't take up too much space or use too many resources.