What is CPU over Clocking


CPU Overclocking is a process to increase the GHz rating of the CPU. The formula to calculate the speed of the CPU is as follows – The product of the FSB in MHz and the multiplier is the speed in MHz.

The FSB is a short form for Front Side Bus. CPU manufacturers have detected a method to raise the effective speed of the FSB. This is done by just sending more instructions per clock cycle. Thus, in every clock cycle, sometimes two or four instructions are sent. This results in increasing the FSB twice and four times respectively. This is of utmost significance. The reason is that when overclocking of the CPU is done, the user deals with the real FSB speed of the CPU and not the effective CPU speed.

When you over clock your CPU, it runs at speeds more than what it was intended to. This creates instability and produces more heat. To attain more over clocks, the CPU needs two things. It needs to be cooled down in order to run stable. It also needs more volts to run at higher speeds with stability. This produces more heat and that has to be controlled with the use of a capable cooler.

An overclocked CPU may seem to run fine and the user may often find the system crash for no reason. This is because the CPU is not able to handle higher speeds and it either needs to be cooled down or more voltages or both. Once that is done, the CPU has to undergo a series of tests to ensure it can run stable at higher speeds. For this, many free stress testing tools are available. Some of them are Prime95, wPrime, OCCT, IntelBurn Test etc.


Stress test calls for proper cooling

Stress testing your CPU for stability after any attempt of over clock is extremely important to ensure your system can handle any other task. Typically, stress testing applications load the CPU to 100% and you can see that in Windows Task Manager. As these programs stress the CPU to its maximum, the CPU will run very hot and proper cooling has to be employed. There are many good third-party coolers are available in the market ranging from 25 to 100+ dollars depending on the manufacturer and whether it is an air or liquid cooler.



Testing for Stability

Most of the stress applications can detect errors and can immediately stop the test and provide a notification to the user that there was a hardware problem. Sometimes, Windows will crash showing a Blue Screen of Death (BSOD) and that makes it clear that your over clock is not stable. If the system is unstable when running a stress test, you should see if the temperature is too much for the CPU to handle and provide more airflow inside the case. If that doesn’t help, you can increase the CPU VCore a notch to see if it can finish the test. If you find nothings makes the CPU stable, you have most probably reached the maximum over clock that particular CPU can handle.

What to know before stress testing

PSU – Before overclocking and stressing your CPU, you must make sure your power supply (PSU) can handle the overclock. Cheap PSUs usually blow up when stress testing as 100% CPU load can easily demand lots of power and cheap PSUs are not meant to handle that. Otherwise you will burn out your CPU, motherboard and might even loss valuable information that would require you to contact a professional data recovery company. Consider purchasing a good PSU from companies like Corsair, Antec, Seasonic OCZ etc.


Cooling – As your CPU is going to heat up like never before (literally, because stress testing applications put the highest stress on the CPU), you must cool it down to attain higher overclocks, stability and longevity. Heat encourages electron migration in transistors and that can severely impact the CPUs lifespan. Apart from good case cooling, get a third-party air or water cooler. For most of the typical overclockers, air cooling is just enough. You can consider coolers from Thermalright, Zalman, Scythe, Noctua etc.

Motherboard – If you want to overclock, it is always better to purchase a good motherboard. This is because it is the motherboard that provides power to the CPU and it should be capable of handling the load. Overclockable boards come with high number of MOSFET power phases to provide reliable power. Cheap or substandard boards are not meant to overclock and may die when overclocking and stress testing.

Stress testing is the only way to make sure an overclocked CPU is stable. If overclock your CPU, you must stress test to ensure stability and if you want to stress test, you need better computer components.

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