What are some alternatives?
When comparing iStat Menus and Open Hardware Monitor, you can also consider the following products
SpeedFan - Hardware monitor for Windows that can access digital temperature sensors located on several 2-wire SMBus Serial Bus. Can access voltages and fan speeds and control fan speeds. Includes technical articles and docs.
Core Temp - Nov 4, 2017 - Core Temp is a compact, no fuss, small footprint, yet powerful program to monitor processor temperature and other vital information.
CPU-Z - CPU-Z is a freeware that gathers information on some of the main devices of your system : Processor name and number, codename, process, package, cache levels.
MenuMeters for El Capitan - MenuMeters for OS X El Capitan 10.11 (and later)
HWMonitor - HWMonitor is a hardware monitoring program that reads PC systems main health sensors : voltages, temperatures, fans speed.
Sidebar Diagnostics - SidebarDiagnostics - A simple sidebar for Windows desktop that displays hardware diagnostic information.