Intel Power Gadget is free and does exactly what you want. It also logs the data.
iStat Mini was $3 I think, and puts that information in the notification widget area. Looks great too.
Then DiskZilla is $30 and does much more than just health monitoring, but does have a clean interface. Upside to paying them is that you can do something about the stats you don't like. Using too much RAM? Optimize it. Low on SSD storage? Remove duplicates and run a disk analysis. Need to get rid of junk apps or sensitive files? Use their app uninstaller to remove ALL files for the applications you're uninstalling and then run a DoD pass on the sensitive file, rendering it unrecoverable.