Is Turning a Powerful PC On and Off Several Times a Day Harmful?

A few normal shutdowns and startups per day are not harmful. Modern computers are designed for this, and turning the system off when you’re finished will save more electricity than any minor wear caused by the power cycles. There’s no need to leave it running just to avoid shutting it down.

You can safely turn it off whenever you’re not going to use it for a while. Leaving it on may be convenient, but it continuously consumes power and adds operating hours to the fans and other components. Just use the operating system’s normal shutdown process, and restart occasionally when updates or troubleshooting require it.

The main possible downside is a small thermal change as the components heat up and cool down, but two or three cycles a day is well within normal use and is unlikely to make a meaningful difference. Since your storage is SSD-based, you also don’t have to worry about mechanical hard-drive spin-up wear. If your power is unreliable, shutting down when you’re away can even reduce exposure to outages or brownouts, though a UPS is better protection.