CPU Overclocking Guide: How (and Why) to Tweak Your Processor

Basic Steps to Overclocking a Processor

Adjusting processor frequency options is usually done through the motherboard firmware, or through a desktop utility provided by a manufacturer. Every platform is different, requiring processor-specific steps for overclocking, some of which we will be covering later on. The general procedure to follow boils down, more-or-less, to:

Step 1: Using a tool of your choice (these tools can be integrated with the overclocking software suite or they can be third-party benchmark and monitoring tools like Geekbench, Prime95, SuperPi, etc.), benchmark and monitor the system as-configured from the factory; this means measuring CPU performance, core and overall system temperatures and voltage usage, within normal operation and stressed or peak operations.

Step 2: Using a tool of your choice (AMD’s Overdrive, Intel’s Extreme Tuning Utility, motherboard manufacturer-specific overclocking software suites like Asus AI Tweaker) increase the multiplier in small increments. Obviously, you need a CPU with an unlocked multiplier for this to work.

Step 3: Run the benchmarking tool from step #1 and check for stable operation.

Step 4: Repeat steps 2 and 3 until you find a multiplier setting that is unstable, or you max out the multiplier available. Then drop back down a notch and run the benchmark again. At some point you may have to start tweaking voltages in parallel with the multiplier (higher frequencies require higher voltages, and the system may not be providing enough juice to the processor to be stable).

Step 5 – Step N: Tweak the BCLK, run benchmarks, tweak other ratios, run benchmarks, tweak voltages, run benchmarks...

A lot of patience is required, especially when looking for performance at the extreme end of what is typically achievable. The system will often become too hot or too unstable to proceed, but there are a lot of variables that can be modified to achieve maximum performance within the hardware's constraints. Many motherboards come with the ability to save firmware profiles; saving profiles, taking screenshots, or writing down good notes is an important part of the process, because there’s nothing more disappointing than spending hours tinkering and then not remembering which settings were the good ones.

Motherboard and Firmware

Apart from the CPU itself, the system’s motherboard is the most vital component in determining processor overclocking performance. First, the most obvious: the motherboard’s components need to be able to handle higher voltages and heat. Also, the headroom for overclocking beyond simple multiplier adjustments comes from how high the BCLK can be set, which depends greatly on the quality of the motherboard. Second, and this is only a concern on the cheapest motherboards, and usually for high core counts, the CPU power connection needs to support the processor's needed amperage. Finally there are the firmware options needed to overclock. Motherboards designed for overclocking have all the voltages, frequencies, and multipliers required, but a generic, business-oriented board doesn't. The firmware options are not quite as important when AMD or Intel’s software overclocking tools are used, so you can get away with a motherboard not designed for overclocking if its components are high-quality, but this means a processor cannot be overclocked beyond what AMD or Intel allow through their tools; extreme performance is harder to achieve.

ASUS 9 Series Motherboards for Overclocking Applications

There are many motherboard manufacturers, models, and capabilities on the market; going by a brand's reputation and reviews can be a good indicator of quality. But because the main driver behind an overclocker’s need for quality components is the motherboard's voltage-handling capacity, the main things to look for is a capable voltage regulator and its components. Each motherboard manufacturer has its own voltage regulation scheme, and there is no standardized format for listing components and capabilities.

There are also a large number of subtleties inherent to the electronic design of voltage regulation circuitry beyond the scope of this article, but without going too in-depth, many manufacturers emphasize a higher number of “phases,” as well as MOSFETs (Metal-Oxide Semiconductor Field-Effect Transistors), capacitors and inductors from high-end manufacturers. The primary controller in a voltage regulator is the Pulse Width Modulation (PWM) controller; this controls the phases/pulses of power flowing through the motherboard. A feedback loop in the PWM monitors the power and thermal state of the system, then modifies the outputs of the PWM to supply the user-defined voltage.

Gene Fabron is an Associate Contributing Writer for Tom's Hardware US. He writes reference material across a range of components.
  • rush21hit
    Look at the voltage setting on those world records. Lots of LN2 involved here.

    Speaking as a former user of Q6600 @3.0 (Corsair Hydro series were non-existent back then) and i7 920 @2.8. Small OC, I know. Since I want my motherboard not get fried.

    Motherboard gets the most hammering in OC. Even the best of the best sometimes failed. Those capacitors can only hold so much. I just want to ensure it also last. Heck, even in normal use, motherboard tends to fail long before any other parts does.
  • blackmagnum
    Careful not to void your warranty. Leave extreme overclocking to the pros.
  • Calculatron
    Ever since the articles on the "E" series of the FX-line-up, I've tried to take efficiency into account. I run a mild overclock of 4.0ghz with just under 1.2V on my FX-8320. I can achieve a 4.7ghz overclock, but I just don't think that the performance gains are worth all the extra heat and stress on the components.
  • Nuckles_56
    There's a typo in the table of record speeds for the CPUs and the respective voltages, as there is no way that the i7 860 got to that speed at 1.152V
  • SinxarKnights
    18275176 said:
    There's a typo in the table of record speeds for the CPUs and the respective voltages, as there is no way that the i7 860 got to that speed at 1.152V

    http://valid.x86.fr/xuxjnn look for yourself. I suspect there was an error reading the voltage but I do not know, CPU-Z calls it valid though.
  • TexelTechnologies
    Its not that complicated but then again I am always surprised by how dumb people are.
  • Murdock4321
    Overclocking used to be pretty complicated and take some trial and error. With all these new processors and new bios', its really pretty easy. I'm still rocking an i7 930 @ 2.85ghz which is rock solid and has lasted me since 2010
  • leo2kp
    i7 970 @ 4GHz here with overvolt. 6 years old and still going strong.
  • jtd871
    How about an underclocking/undervolting guide for those that want efficiency rather than performance?
  • anbello262
    Well, isn't the procedure exactly the same, just lowering mult and volt instead of rising it? The stability concern (freq/volts) and the iterative methodology is the same, right?