What are the dangers of high CPU voltage?

Question

I have a i7 6700k Skylake and I have her overclocked at 4.7GHz with 1.7V. I've seen people saying that you should be wary of putting the voltage over 1.5V, but they all seem to be related to core temperature. I have a really good cooler and just now when I ran a stress test at 4.7GHz 1.7V it didn't get over 55C. Is high voltage a problem if you can keep the temperature down?

Answer 1

The conductivity of a semiconductor is depending on it's temperature. By increasing the voltage the free charge carriers move faster and collide more often with the grid.

So by turning up the voltage, the conductivity increases, more currency can flow and the processor gets hotter. Even if your cooling system keeps the overall processor temperature low, single capacitors can still overheat and blow.

Your processor will not get any faster by increasing the voltage, although this might be necessary, if you're increasing the frequency. The optimum would be to keep the voltage as low as possible, but as high as necessary.

Answer 2

There are always risks when you operate a device outside the parameters defined by the manufacturer. In the case of overvoltage there are risks to the device itself and to it's reliability of operation. Combine overvoltage with a higher operating frequency and you compound the risks.

The CPU is pretty good at protecting itself from high temperatures that occur under normal operation but there are other dangers it can do nothing about. Overvoltage may result in localized high temperatures that contribute little to the average measured temperature. It is also well known that excessive voltage itself can damage electronic devices, even when the other operating parameters are well within safe limits.

A somewhat higher voltage will often improve reliability when overclocking but you must be careful not to go too far. More isn't necessarily better.

A CPU operating under abnormal conditions, such as higher frequency or voltage, may make mistakes. Things become very complicated at the frequencies used in a modern CPU and it is very possible that a specific voltage may be misinterpreted as a 1 when it should be a 0, or the reverse. Most software has a zero tolerance for error and the results are unpredictable. Even a single error during hours of operation can have serious consequences.

An error may result in a system or application crash. That is serious but you at least know there is a problem. Potentially more serious is an error that initially goes unnoticed. When doing calculations a single error can cause a chain reaction of wrong numbers. You really don't want this to happen when the computer is doing your tax return.

A good rule is to never overclock or overvoltage a computer that is used for important purposes. For a computer used for entertainment purposes, such as gaming, the risks may be justified. For financial calculations, clearly not.