You have a 5500U, that's why it power throttles. It will throttle to try to stay below TDP, and those CPUs have a pretty low TDP. You can use ThrottleStop to try to prevent that but in my experience it won't always work.
83C is pretty high for a desktop, but it looks like you're on a laptop, and those normally run hotter due to cooling constraints, so I wouldn't worry. Either way it's not hot enough to kill a CPU, might have a small effect on the expected lifetime but it will probably die of other causes or simply go unused before the CPU dies.
If this was a desktop CPU running at stock speeds then 83C would be worringly high. Not because it will damage the CPU, but because it's a sign that something is not right with the cooling. For example, my i7 920 got up to about 76C when stress testing with the stock cooler, and that's a 130W TDP CPU. Newer CPUs run cooler since they are far more efficient. Even the high-end i7 8700K only has a 95W TDP. So having those kind of temps on any recent or semi-recent Intel CPU on a desktop would be a sign that either the cooler needs to be cleaned, the fan needs to be replaced or the thermal paste needs reapplying. Or someone just did an awful job with cable management.
On a laptop like he seems to be on though, it's a lot more normal. It's hardly optimal, but decent cooling on laptops is often sacrificed for portability.