IMPORTANT: This guide is only for Bloomfield, i.e. LGA1366, based i7s. For Lynnfield, i.e., LGA1156, based i7s or i5s you can use this guide, but be warned that the procedure may be slightly different due to the different hardware. Alternatively you can wait until I write my dedicated i5 overclocking guide when I get some i5 hardware to experiment with.
After Overclocking my i7 920 D0 to 3.8 GHz I thought I would start a guide on how to overclock the i7 920 D0. This will involve lots of use of the "Edit" function, and please if anything is wrong or want to add anything to this please don't hestiate to post a reply. Consider this a work in progress.
If anyone has any experience with other i7 revisions and feel that the process is so different as to justify a new section please reply.
There are a few concepts you will need to understand for overclocking, here I list them and explain what they are:
- BCLK or Base Clock is the Base clock the motherboard runs at. This is defined by the model of CPU, and by default is set to 133 MHz for the i7 920 D0, for a total speed of 2.66 GHz.
- CPU Multiplier: This is a function of SpeedStep, the Intel technology that underclocks your CPU when it is under low load. In order to change the current frequency that the CPU is running at the computer will change the multiplier. The multiplier with run at 20 for the i7 920 D0 when the CPU is running at full speed.
- Intel TubroBoost this function gives an extra boost of speed to the processor, by changing the maximum multiplier from 20 to 21.
- Vcore voltage: this is the voltage which the motherboard supplies to the CPU rails. You will need to adjust this if the CPU is taking to much power to maintain destinct logic levels. (i.e. it will become unstable)
- DRAM voltage: this is the voltage suppiled by the motherboard to the DDR3 RAM.
- RAM Multiplier: this is the muiltiper of the RAM from the baseclock.
- Memory Timings: without defining these your RAM will run at stock or some artibratory value defined by the motherboard. You will need to adjust them to match the specifications given to on your RAM, for example my RAM, Patorit Viper CL8, has times of 8-8-8-24.
- PCIe clock. This should be set manually to ensure that the graphics cards and other PCIe devices function normally. It is the clock at which the PCIe slot operates under.
The theory behind overclocking is rather simple. You increase the base clock and multiplier until the speed of your CPU is running at the desired point.
The are a few things to consider however, the RAM is affected by the base clock as well, so you must make sure it is running as close its designed timings, frequency and voltage. You computer will also have trouble under load if there is not enough voltage, so you will need to increase the voltage to Vcore if you cannot get the machine stable.
Thermal output: an aftermarket cooler is a must when overclocking because the stock cooler that comes with the CPU is not only loud, it is not very efficent. Your cooler, be it water or air, will determine how much you can overclock your CPU. The better your cooler, the more you can push your chip, because the temperatures will be lower. I will explain this more in detail later.
In order to begin it is recommend you have the latest drivers. What we require is a stress testing application. I generally use OCCT, but there are other applications, all which have their advantages and disadvantages. I like OCCT because of it's ease of use, and the wealth of information it provides.
I also run CoreTemp so that I do not have to have my moniter on to check the status of the temperatures (I have a G15, which CoreTemp supports).
My friends and I have developed a full proof testing method, and we call it POST, Boot, Prime, or PBP. There are three stages of stablity:
- POST - The computer boots but is unable to start an operating system.
- Boot - The computer is able to get into the operating system
- Prime - the computer can run fully loaded on 8 threads (for an i7) for an extended period of time.
The goal is to get Prime stable, because that means your computer will not be pushed to breaking point. My friend once got his system boot stable so that he could run GTA IV on a Core 2 Duo. He was able to play for about two hours then he would need to turn his computer off for about an hour or leave it idle to let it cool down!
Your motherboard is key to any overclocking operation. It needs to be robust enough to handle the abuse, and configurable enough to allow you to overclock the system. I personally recommend the Gigabyte X58-UD5, but also worth considering are the ASUS Rampage II Deluxe, and the ASUS P6T Deluxe V2. Even a ASUS Rampage Gene will work well, if you're pushed for space. All I can really say is shop around, read reviews, and find one that best suits your needs.
Secondary, but just as important, is the processor. The i7 920 D0 is recommended at the moment because it is the cheapest of the i7 range, and handles well over a wide temperature range. However it is reaching it's EOL, so when this happens we will need to find another i7 to work with.
Then there is your RAM. I recommend you get CL7 or CL8 RAM at around or above 1600MHz. From the information I have read there is a little point getting faster RAM, however there is no harm in it, apart from to your bank balance.
Keeping your CPU and RAM cool is the most important factor. The RAM, if set to stock, the manufacturer's defined times, shouldn't need active cooling, however the CPU will.
If you can afford it you can go watercooling. The advantage to this is due the mechanics of a watercooling loop it is possible to cool the CPU to a level lower than the ambient tempeture of the case.
Air on the other cannot get the tempeature any cooler than ambeint. This is especially important if you live in a hot country or use your computer in a hot boiler room.
If the CPU gets too hot, it will ceese to function properly, and will trigger a thermal tilt-bit, which will immediately shut down your computer, or worse, the chip will melt and become permanently damaged.
I will not give you suggests for cooling as this comes down to personal preferance, budget, and sometimes the clearance provided by the case.
Don't be afarid to ask questions when it comes to cooling. For example in order to fit my heatsink in my case I needed to remove the 220mm fan from the case, and it still functions prefectly.
Right now we have the preparation underway, I will assume you have a working system with the desired cooling and components. I will also assume you have installed an appropriate version of Windows, and OCCT.
Please understand that as I go through the BIOS you may find your BIOS is slightly different.
First off there is a we bit of maths. To start, get the timing and recommend frequency settings for your RAM. Say you bought Patriot Viper CL8 RAM , as I did, then your documentation would say your times are 8-8-8-24 and the RAM runs at 1600MHz.
Now RAM is quite confusing in that lower the numbers means lower latency, but for stability and speed you actually want that number to be higher, i.e. higher latency. Not to high however, as then your cannot do enough operations. To fast, and your RAM may become unstable at high clocks, to slow, and your RAM will take to long to do memory operations. I find the best balance to be CL8 RAM.
The price is usually a good indicator of which RAM is better, but only if you stick to the same brand. And remember, this is only a rule of thumb.
Some RAM has a feature called Extreme Memory Profile (XMP), that automatically sets the RAM to the relevant latency and speed. Now you may be thinking "that's great why don't we just use that?" Well to understand this we must first understand multipliers and the base clock.
Your computer has a base clock, which both the RAM and CPU's clocks are driven off. In order to get that final number, i.e. 1600MHz RAM or 2.66GHz (2660MHz) the modules have a multiplier, which multiplies that clock by a given factor.
As I said earlier, by default the maximum multiplier is set to 20, for the Core i7 920 D0, and the base clock runs at 133MHz. This results in a speed of 2660MHz.
Now the RAM applies the same method. To get 1600MHz for the RAM a multiplier of 12 is applied, resulting in 1596MHz.
Now in order to overclock, we will be increasing the base clock. This means, if XMP was enabled, and the multiplier of 12 continued to be applied when you set the base clock to 200MHz, then the RAM would be running at 2400MHz, which could be damaging the the module. For this reason, to be on the safe side and ensure that the modules don't get damaged, we will manually define the memory timings and multiplier.
There is another danger related to RAM, and that is voltage. Please make sure you set the DRAM voltage manually as well as you could damage the module if you leave it on automatic.
So now, it is time to plan your set a goal for your overclock. Bare in mind that your cooling plays a very important factor. You cannot get 4.0GHz on every cooling system. I would start at a figure you know is obtainable, say 3.0GHz, and work up from there until you find a temperature range you are happy with.
At the moment you have your RAM speed, and desired clock speed. Let us assume you have 1600MHz RAM and want to achieve 3GHz. What you want to do is take your desired CPU clock and divide it by 20 (or the multipler for your relevent CPU), the maximum multiplier:
3000 / 20 = 150
So this will be your base clock. Now then, we need to work out the required multiplier for your RAM. The multiplier unfortunately has to be an integer, so you will either have to get a multiplier of 10, and run your RAM at 1500MHz or a multiplier of 11 and run it at 1650. Some motherboards, like mine, only support even integers, further restricting your ability.
So that's the math, let's get in there and do it shall we?