Open Hardware Monitor
Monitors temperature sensors, fan speeds, voltages, load and clock speeds, with optional graph.
Translucent provides detailed real-time information about what is going on inside your Mac.
translucent provides detailed realtime information about what is going on inside your mac. at any given time translucent displays how much each one of your processors is being utilized, detailed information about how your memory is being used, how much data is being sent and received on your network interfaces and how much is being read and written to your hard disks. it displays itself as small addition to your status bar with tooltipstyle detail popups; displaying more detailed information on any of the sensors in the status bar. translucent also displays its sensor information in windows for larger and more detailed information viewing.
Productivity Utilities System and Hardware
system-information hardware-monitoring
Monitors temperature sensors, fan speeds, voltages, load and clock speeds, with optional graph.
Free Open Source Windows Linux Mono
this is a port to os x el capitan 10.11 of menumeters by alex harper.
Free Open Source Mac OS X
AMD System Monitor is a comprehensive application which displays all the information about your system AMD products (and Intel CPU). It generally provides the overall...
Free Windows
This is a Windows version of the Data LifeGuard Diagnostics. It will test WD internal and external drives. In additional, it can provide you with the model and serial of WD drives attached to the system.
Free Windows MS-DOS
Magican Lite is a free system monitor utility. It could help users monitor CPU and memory usage, watch on download and upload speed and detect temperature of CPU and GPU from the tiny and flexible floating window.
Free Mac OS X