system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What is the science behind overclocking a CPU?

What actually happens behind the scenes, inside the computer for it to overclock? 

Edit: Went to sleep and came back to crap ton of answers. I appreciate it truly and will read each one. Thanks!
gpt
Imagine 500 workers in your company.

Each worker fills out a form, their work. You give them 10 minutes for one form, since some guy has calculated that to be the best "base clock speed" of 3000 forms per hour.

You actually sell your company to other people and they perform as advertised, but every company you sell has DIFFERENT workers (obviously).

It is still kind of the same company though.

It turns out, your workers fill out the form in 8 minutes on average and then meet in the hallway to chat.

One of your customers thinks he can 'overclock' his company: he tells all the workers they only have 9 minutes to fill out the form.

Works great, there were still resources left in that company and now you have a company that gives 3300 forms per hour (10% increase).

One of the customers friends got wind of the overclocking and tries it with his company. It's horrible: the workers take 9 minutes on average to fill out a form, so on average they should meet the 9 minute requirement, but they have no more time to chat, get depression and burnout. Eventually a worker quits because he had enough.

This is where your company becomes unstable and locks up, e.g. the overclocking went too far, not enough untapped resources were available, mistakes are made that cannot be undone, etc.

The 'potential' for overclocking is different for each model and even differs with each CPU sold.

If you increase the clock speed, some signals can get lost in transit if the physical layout of your CPU is 'bad' (this means that one of the circuit paths during the lithography process was less than ideal, too thick or too thin for example) so you also need to increase voltage, but THAT in turn increases temperature and also, since each circuit path is an antenna, the influence one circuit path can have on another. This can go to a point where to circuits cancel out each other's signals when they 'transmit radio signals' too much. That 'interference' is what cannot be overcome by any means other than designing the CPU differently.

In essence, there's potential to do stuff faster. How MUCH is determined by the quality if the design AND the individual 'print' of your CPU.

To get your CPU to a stable processing speed that is higher than what the manufacturer intended is tricky but can usually be done reliably without damaging the component by

1. increasing the frequency until failure
2. increase voltage to strengthen signal
3. repeat 1+2 until failure because of interference

The reason a manufacturer picks a certain clock speed is simple: yield.

One printed wafer gives a certain percentage of functional dies (the heart of your CPU). Each die is tested to run at the base clock  speed. The better the design and the better the manufacturing process as well as how carefully chosen the clock speed is: more dies per wafer = more cash.

The idea is to get the best die per wafer that can reliably be produced with as few losses as possible.