Grantm56

This may be an instance where a bottle of hand lotion near the PC is legitimately explainable.

Depends on what you mean by worry. I would argue that you shouldn't need to baby your processor with that caliber of a cooler unless you're having issues.
 
Your CPU won't lose any performance until it hit 90C. It will run to its highest ability up until it hits that temperature. It will boost to higher clockspeed when it has thermal headroom as well.
 
AMD calls their boost tech "Precision Boost 2" - more info here. There are other limits (amperage, wattage) and the nature of the workload - higher boosting is typical on shorter tasks.
 
For persistent multi-threaded tasks like gaming, your clock speed is typically more level and less "boosty", not jumping up and done as much. Your temps should be stable. 
 
I wouldn't worry at all unless you get persistent temperatures in the high 80s. And with the data provided, it looks like your CPU is adequately cooled. 
 

The 5900x will thermal throttle at 90C. You're not anywhere near there, with max temps of 79. That's great!

The 5900x is a chip that runs hot, but it's also being cooled very well with a beefy cooler like the AK620. You shouldn't need to worry at all. 
 
 
 
 
 
 

source - this article

The 5900x will thermal throttle at 90C. You're not anywhere near there, with max temps of 79. That's great!

The 5900x is a chip that runs hot, but it's also being cooled very well with a beefy cooler like the AK620. You shouldn't need to worry at all.