VitalSigns for Mac Is a Notification Center Widget That Tracks System Temperature, RAM, and Fan Speed.
Mac: Keeping track of the various sensors on your Mac is easy enough with System Monitor , but if you’re looking for a free and easy option, VitalSigns dumps information from various sensors into your Action Center.
VitalSigns is not a complete system monitor, instead it just monitors a small group of details: temperature, fans, and memory. In terms of temperature, you can choose which sensors are displayed for which boards, but otherwise there is no particular customization option. Considering that VitalSigns is free, that’s not a bad thing, and if you’re just looking for a quick way to keep track of some of the system’s details, it gets the job done.
VitalSigns (free)