EDITED - I put the wrong details in here first time around - sorry!
It’s called OpenHardwareMonitor. You can find it on google - link below. It has a “normal” hardware monitor screen like this:
But what I copied above is a great little thing it has called the gadget. Basically you can select any stat from the full monitor and add it to the gadget - right click like this:
Then you can choose to show the gadget from the view menu
Once you show the gadget, you can minimise the full monitor (don’t close it or it will close the gadget too). If you then position the gadget where you want it, it will stay there all the time and even re-open there when you shutdown/restart. I leave mine sitting on my second monitor all the time.
Just in case - install at your own risk (I’ve not had any problems)