Goals

The variety of users reading this guide is vast, and each user’s goal will be unique and specific to his/her needs.  It would be impossible for me to address every user’s specific needs.  But I’ve attempted to be as broad, yet specific as possible.  My goal is to assist the maximum number of users as possible, despite your specific needs.

Based on user feedback from the previous version of this guide, I decided to better address overclocking with power features enabled.  The easy answer was to follow the old guide and then attempt to enable your power features afterward, but that rarely worked when approaching the limits of a given system.

Just as before, if you want to maximize your overclock, you should disable all the power saving features in the BIOS as detailed in step 1.  However, if you’re after a more moderate overclock, and you’d like to save power (especially while your system sits idle) you can leave those setting enabled.  Just follow the guide as written (I’ve added tips for you along the way) to find your best settings.  While your potential overclock will be more limited, the bennefit will likely be worth it to many of you.

Terminology

I’d like to start off by writing briefly about the BIOS and more specifically, differences in terminology between the different manufacturers.  Obviously there are too many motherboards on the market to show you every single one in this guide.  But looking at boards from the four top manufactures, we should be able to better identify specific terminologies used by each.

Below I’ve created a table comparing the terminology used by the four major enthusiast motherboard manufacturers.

A comparison of BIOS terminology used by four top manufacturers

***A brief note about Asus.  Asus makes multipliers a little more confusing in this guide because the BIOS doesn’t show the ratios at all, they only show the speed of the item based on the bclock set.  This requires a little additional math on your part while using this guide.  Please be aware of this difference as you progress***

Throughout this guide, I’ll be referring to the terminology used by Gigabyte because it is most familiar to me.  This top section is to be used for reference so that you know what I’m referring to you when your BIOS options don’t match my instructions.

Understanding “total system performance”

Before we go into how we overclock these CPU’s let us look at what determines how fast your whole system will run.  CPU frequency is very important.  However, there are many other factors that play into your total system performance.  All of your primary BIOS overclocking revolves around the Base Clock or “bclock” and clock ratios.  The base clock’s default speed for all P55/H55/H57 based systems is 133MHz.  Typically we shoot for an overclock in the range of 200MHz bclock….but doing that has a major effect on a number of things…

A map of the Lynnfield die

CPU frequency = bclock x CPU clock ratio

This is a biggest change from the old LGA 775 where FSB and CPU clock ratio determined the CPU speed.  The base clock is similar to the FSB but also has some key differences.  The bclock is the basis for all the other frequencies discussed below.  So as you increase bclock, you’re affecting the speed of many components.

The CPU speed is the primary concern for day to day, noticeable performance gains, but not the only factor that determines how fast your PC will run.

QPI frequency = bclock x QPI clock ratio

QPI or Quick Path interconnect is the Intel communication path between the CPU and the P55 chipset on the motherboard.  So all devices not controlled on the CPU die itself have to communicate with the CPU via the QPI.  For instance, the memory and PCIe controllers are built into the CPU, so the memory & graphics card bandwidth are not limited by the QPI, They have their own direct link to the CPU.  However, the P55 chipset on the motherboard controls all of the storage devices, NICs, audio devices, USB devices, etc….they all have to communicate with the CPU via the QPI.

The good news here is that Intel created the QPI for CPU to CPU communications for use in multi CPU servers for the enterprise market.  That means the bandwidth they built in is HUGE, and in reference to overclocking, higher QPI speeds don’t affect performance enough to notice in day to day activities.  So I NEVER run the QPI beyond x32, with the bclock at 200MHz this would result in the QPI running at 6.4GHz which is plenty for anything you might throw at it.

Memory frequency = bclock x System Memory Multiplier (SPD)

Memory is shown in the BIOS as a multiplier of 6, 8, 10, etc…  This represents the multiplier to reach the DDR speed.  So, a stock 133MHz bclock with the multiplier of 8 would result in a memory speed of DDR3-1066.

DDR – The other part that can be quite confusing for users who are not familiar with DDR technology is the difference between the memory clock speed and the memory’s DDR speed.  For instance, DDR3-1600 actually runs at 800MHz, it’s just that DDR (or dual data rate) technology allows the memory to process twice per clock cycle.  Back when we switched technologies from SDRAM to DDR for the first time, the manufacturers started saying DDR-400 when it ran at 200MHz because it was better marketing to sell their memory over the older SDRAM technology.  This is why CPU-Z shows 800MHz for your DDR3-1600, or 1000MHz for your DDR3-2000.

Memory speed and bandwidth can have a huge effect in some applications, and negligible impact on others.  But overall, top shelf memory is one of the worse items you can spend your money on from a value perspective.  Faster CPUs and GPUs will give you much more performance for your hard earned cash.

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