System Instability and Overclocking

[Qwright10]

What causes system instability when overclocking a CPU above a certain clock with adequate water cooling? I ordered an NZXT Kraken X52 and I plan to overclock my Intel Core i7-8700K but wanted to know what the highest achievable clock is without causing system instability.

[CookieMaster]

1 hour ago, Qwright10 said:

What causes system instability when overclocking a CPU above a certain clock with adequate water cooling? I ordered an NZXT Kraken X52 and I plan to overclock my Intel Core i7-8700K but wanted to know what the highest achievable clock is without causing system instability.

Depends on your system and cpu. Silicon Lottery. I would try for 5ghz first and see if you can get that stable at your max voltage you want to go to. (anything above 5.2 might be very hard ) 

[Qwright10]

1 minute ago, CookieMaster said:

 max voltage you want to go to. (anything above 5.2 might be very hard ) 

 

Why does overclocking require a higher voltage anyways?

[CookieMaster]

1 hour ago, Qwright10 said:

Why does overclocking require a higher voltage anyways?

Set clocks need a certain amount of voltage to operate. When you step it up, it will require more voltage to be stable and operate. 

[Qwright10]

Just now, CookieMaster said:

Set clocks need a certain amount of voltage to operate. When you step it up, it will require more voltage to be stable and operate. 

So power to the CPU is DC and the oscillator/quartz crystal creates the oscillation or clock, correct?

[CookieMaster]

1 hour ago, Qwright10 said:

So power to the CPU is DC and the oscillator/quartz crystal creates the oscillation or clock, correct?

TBH I have no clue. 

[LordofSavages]

There is no set "magic oc values" for any processor. The simplest way is increase multiplier by 1 then add a lil voltage then repeat until you hit a thermal limit or you crash. If you do get super lucky and get 5.4Ghz and temps are fine, then just tune the voltage further. You shouldn't be looking at the highest stable clock for others but instead what the highest stable clock for you at a safe voltage and temperature

[whoisit1118]

Make sure to delid the 8700k before you attempt your 5.0ghz+ overclocks.

[Qwright10]

Just now, whoisit1118 said:

Make sure to delid the 8700k before you attempt your 5.0ghz+ overclocks.

Does the Intel heat spreader hold too much heat to overclock above 5GHz?

[CookieMaster]

1 hour ago, whoisit1118 said:

Make sure to delid the 8700k before you attempt your 5.0ghz+ overclocks.

Why? I didn't have no problem if you have a good cooler. I guess it depends if you are pushing more than 1.35 v too.

 

1 hour ago, YaqinHasan said:

There is no set "magic oc values" for any processor. The simplest way is increase multiplier by 1 then add a lil voltage then repeat until you hit a thermal limit or you crash. If you do get super lucky and get 5.4Ghz and temps are fine, then just tune the voltage further. You shouldn't be looking at the highest stable clock for others but instead what the highest stable clock for you at a safe voltage and temperature

And I recommend that you go to your max voltage and go from there, see if a high clock is stable 

[SquintyG33Rs]

7 minutes ago, Qwright10 said:

So power to the CPU is DC and the oscillator/quartz crystal creates the oscillation or clock, correct?

yeah kinda. but the clock isn't the input power at all and it's not a simpel quarts crystal (since those have a set frequency intrinsic to the material itself). it's like a separate line that controls the trigger of when each step can happen to give time for earlier ones to be finished before proceeding. this "travel time" is the source of the instability and the thing the voltage compensates for.

[Coaxialgamer]

7 minutes ago, Qwright10 said:

Why does overclocking require a higher voltage anyways?

That's a bit of a complicated answer , but here's my best shot:

 

CPU's are divided into stages , through which instructions go through when executing . Coffee lake has 14 such stages . The actual clock speed is determined by the maximum amount of time it takes to go through one of these stages . If the delay ( TPD ) is 0.5ns for example , then the max clock will be 2ghz .

 

If you look at the datasheet for any logic IC on the internet , such as this one and scroll down to the AC characteristics ( switching characteritics , page 5 )  , you'll get propagation delays depending on voltage. By increasing voltage , the delay goes down .This is the same with CPUs.

 

Now from an electrical perspective , while i'm not engineer , it has to do with the threshold voltage being hit in a lower amount of time . Transistors operate as HIGH or LOW ( 1 or 0 ). For TTL , anything below 0.8V is LOW , and anything above 2V is HIGH .By being at a lower voltage , that threshold is hit in less time