I just came across the Intel Extreme Tuning Utility. I am using an i5-7600K because, when I built my PC, it was the best I could get with integral graphics. I didn't want to pay for a separate GPU if I didn't have to.
I'm not a gamer. Photo processing is my most processor-intensive activity. If I overclock to, say 4.0 GHZ, will I see any real effect or improvement?
The good news for you is that your processor is supported by XTU.
You may want to review these docs: