5% load on a 12-core, 24-thread CPU means that something single-threaded is loading your processor. Your processor is boosting as intended.
And no, it won't shorten the life of your CPU much, when gaming would put much more load on your processor. Provided the cooling's good, it's rare for a processor to fail by itself during its useful lifespan.
Find out what it is in task manager, if needed.