There is a lot of "I think" kinda stuff presented as facts when it comes to the internet.
Overclocking is very much like that.
Let me explain what I have learned (Meaning, you make your own decision what to believe, I just tell you what I do and what it is based on):
Overclocking is increasing the speed at which transistors open and lock signals in order to create binary 0 and 1. The reason you WILL void your warranty if you do this (regardless of increase in voltages or not) is because the transistors are running outside of the parameters that the manufacturer has calculated that they should survive for at least that amount of time that they are on warranty.
Generally speaking, this is not an exact science, and this is why some CPUs die even with no overclocking and others run fine for years with heavy overclocks, and thus the void in warranty.
There are a few things to consider when overclocking:
-In the temperature department: Average temperatures, Maxixum temperatures, BURST (or micro second) maximum temperatures are some.
-In the voltage department: Mostly Vcore and LLC (LLC tends to be the oine people ignore more often and the one that kills cpus).
-Ambient temps.
-Workload.
You can think of overclocking like lifting too much weight. At what point are you going to break something? No idea, but you can get some average safe weight and some average dangerous weight.
Same here. Each CPU should be able to slightly Overclock with no problem (In the case of AMD, XFR is basically doing it for you in most cases anyway, and it is covered by warranty). The minute you have to increase more Vcore/LLC to gain lower increases, you are going too far, and the CPU WILL degrade.
The question is not if it will, the question is by how much and how fast.
Because CPUs are rated mostly for 10 year lifespan at stock (not warranty, expected life), if an overclock decreases that to 9.2 years, most people will not even know what happened (also, bare in mind that when a CPU is failing due to an overclock it will usually start being unstable first, meaning you will have to lower the overclock to keep it stable anyway).
That is for CPUs.
For GPUS? Not worth overclocking. Ever (unless it is a factory pre applied overclock). Here is why: If your GPu cant keep up the frame rate over 30 FPS, overclocking it wont make it run smooth.
If it is running at 200+, the extra 30 frames is worthless for the risk of glitches and crashes.
If it is running at 60, the extra 5 wont make a noticeable difference either.