Intel Core2Duo 775 Platforms

Overclocking Intel Core2Duo platform

It is well known fact, that architecture of C2D has a big potential for overclocking..Here Below is a brief explaination on how to overclock your Core2Duo.

Getting started

To perform a good overclocking, is initially a good motherboard, then the processor of course, and finally the memory are required.

Intel make use of basebfrequency generated by the chipset of the motherboard, called the FSB for Intel(HTT for AMD ones).
Early C2D work with a FSB of 266 MHz, this initial frequency is multiplied by the multiplying coefficient of CPU, to provide the final frequency for the CPU.

E.g.
An E6300 that runs at 1.86 GHz, is the result of 266 x 7 where 7 is the coefficient of CPU (can’t be increased).

you may have heard of these popular terms: FSB1066 and FSB1333. These are the names commonly given to frequencies of 266 and 333Mhz C2D as the technology used by Intel today can make transit four times more information compared to Pentium 3 making use of the same frequency. This is the famous "Quad Pumped" bus., providing a fourfold increase FSB base of the motherboard.
E.g
The FSB1333 bus : 333 x 4.

From these notes you have certainly realize that to increase the frequency of CPU, you must increase the FSB, but the problem is that all frequencies are multiples of this base frequency: PCI Bus and PCI Express...etc, increasing the FSB without further precaution, increases at the same time all others , quickly making your PC very unstable.

Choosing your motherboard

For any overclocking purposes, it is better to buy an advances motherboard.
Here is a list but the most successful motherboard allowing you to achieve a successful overclocking on Intel C2D:
The P965 and 975X, the new P35 running on FSB1333.
For Nvidia: The 680SLI and 650SLI are good choices.

Don’t worry all these chipsets, implemented will support an FSB of 380/400 MHz.

The processor

As decribed above the frequency of the processor is the result of the operation FSB x coefficient, to increase the pace of CPU, we must increase the frequency of the FSB base, as the coefficient of the processor cannot be change.

But the coefficient still is a serious matter concerning the choice of processor you want to use for overclocking.

For example:
Imagine that you are in possession of a motherboard can hold a stable FSB of 350MHz.
Using a E6300 (* 7), overclocked this way, you get 350 x 7 = 2450 MHz
Using a E6400 (* 8), overclocked this way, you get 350 x 8 = 2800MHz

To overcome a possible weakness of the motherboard about its capacity to increase in frequency, we must choose a CPU with a high coefficient.
E4300 or E4400 should be fine.

Respectively clocked at 1.8 GHz and 2 GHz, they operate with a basic FSB200 (FSB800 Quad Pumped) and therefore having a coefficient of 9 and 10 respectively.
Comparison:
With the E6300 you get 2450 MHz.
With the E4300, you get 350 x 9 = 3150 Mhz
If your CPU hold this frequency, you are above a Core 2 Extreme X6800, the only difference will be concerning the L2 cache , the X6800 is still better than the E4300.

These eatimation still remains theoretical, many cards will reach an FSB at 350 MHz, as it is also possible that your processor never gets to exceed 2800 MHz

Memory

Memory

The case of the memory is more delicate.
Better have some high quality stuff if you want your overclocking to be successful.And more importantly, it will depend on the chipset of your motherboard and bios.
For example, the excellent P965 RAM requires a high frequency, because in most cases it is impossible todesynchronize RAM, it should therefore be able to collect the increasing frequency.
With Nvidia, the 680 and 650SLI have more flexibility in this area, it is possible desynchronizing memory by setting the value of certification through an option in the bios ( "INLINKED", for example, on nforce 650 / 680)
Like the CPU, the frequency applied to the memory is the result of a calculation based on the chipset FSB.
It is the bios which apply a ratio depending on the type of DDR2 it detects (via the SPD)
For DDR2-667 (which runs at a frequency of 333Mhz real) the ratio applied is 5 / 4 for a FSB266: 266 x 5 / 4 = 332
If you increase the FSB to overclock your processor without further precautions, you also increase the frequency of the RAM.
Let our example of the FSB be 350.
350 x 5 / 4 = 437 Mhz.
Be aware, your RAM will neve attain this frequency, the PC will crash before arriving at this value.
Hence the importance desynchronizing memory, or via a lower ratio (case of P965) or by using the appropriate option in the BIOS. (ratios are found mainly on motherboards based on Intel chipset)
Keep the same example, but with DDR2-800 (400 MHz actual) and forcing the bios in the ratio for DDR2-667, the frequency of 437Mhz can go with the DDR2-800 quality.
With an E6400, you would get a great overclocking.
To summarize, with an Intel chipset, take at least DDR2 800.
With Nvidia 650/680, you can settle for DDR2 667, but not less.

Prepare overclocking

Enter the bios and switch to manual setting the FSB.
Block the pci bus frequency to 33MHz.
Block the frequency of the PCI Express bus at 100Mhz.
Disable all options "spred spectrum"
Disable support "C1E"
Disable "Vanderpool technology (VT)
CPUZ install this software you will need to follow the evolution of frequencies
CPU, but the ram. http://www.cpuid.com/cpuz.php

Preparing your PC to be overclocked

Enter bios and switch the FSB to manual setting.
Block the frequency of PCI bus to 33 MHz.
Block the frequency of the PCI Express bus at 100Mhz.
Disable all spred spectrum options
Disable support "C1E"
Disable Vanderpool Technology (VT)
Download and install CPUZ ,you will need this software to monitor frequencies changes of the CPU, and most importantly of the RAM

http://www.cpuid.com/cpuz.php

Start overclocking

Choose for a ratio of memory that leaves the memory frequency below its true value (if you have the DDR2 800, set it to DDR2-667)

Gradually increase the FSB basic level by 10MHz.

Check systematically changing frequencies via CPUZ, watch especially the frequency of your RAM, do not exceed the certified frequency, use lower ratios to continue if necessary.

Test your PC with hardware consuming software (Super Pi, OCCT, etc.), to detect any instability.
Go back to the FSB previous (stable) state if needed.

If you are not satisfied by the result, proceed as follow: Test the limits of each of the key elements of overclocking: The FSB, the CPU and RAM.

Once these respective limits are known, we can proceed with a combination of these results.
To go even further, we must adjust the voltages supply of each components. But that means, going through some advanced overclocking. Note that with the C2D, you are able to increase frequency leaving the Vcore to the original value (up to a gain of 20 to 40% of additional frequencies).

Good overclocking Guys!!!!!!