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Core 2 Duo Overclocking Guide

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The CPUs:

A Core2Duo CPU (Allendale/Conroe) are 65nm cores, so they will need lots less voltage than for instance 939 San Diego Core CPUs (90nm). Stock is 1.25, they are rated from 1.1-1.372 Vcore according to Newegg. Safe Vcore for overclocking on a good cooler should not exceed 1.55 Volts for 24/7 use, also because these chips tend to get extremely hot on higher voltages. Best would be if you stayed around 1.5 Volts maximum for day to day use, but in the end it all depends on the Temperature you get.


Temperature Monitoring:

1.) Core Temp

2.) Intel Thermal Analysis Tool


Dual Cores:

E4300 = 1.80GHz - 2MB L2 Cache - 9x - 800 FSB

E4400 = 2.00GHz - 2MB L2 Cache - 10x - 800 FSB

E4500 = 2.20GHz - 2MB L2 Cache - 11x - 800 FSB

E6300 = 1.86GHz - 2MB L2 Cache - 7x - 1066 FSB

E6320 = 1.86GHz - 4MB L2 Cache - 7x - 1066 FSB

E6400 = 2.13GHz - 2MB L2 Cache - 8x - 1066 FSB

E6420 = 2.13GHz - 4MB L2 Cache - 8x - 1066 FSB

E6540 = 2.33GHz - 4MB L2 Cache - 7x - 1333 FSB

E6550 = 2.33GHz - 4MB L2 Cache - 7x - 1333 FSB

E6600 = 2.40GHz - 4MB L2 Cache - 9x - 1066 FSB

E6700 = 2.66GHz - 4MB L2 Cache - 10x - 1066 FSB

E6750 = 2.66GHz - 4MB L2 Cache - 8x - 1333 FSB

X6800 = 2.93GHz - 4MB L2 Cache - Unlocked - 1066 FSB

E6850 = 3.00GHz - 4MB L2 Cache - 9x - 1333 FSB

Quad Cores:

Q6600 = 2.40GHz - 2x4MB L2 Cache - 9x - 1066 FSB

Q6700 = 2.66GHz - 2x4MB L2 Cache - 10x - 1066 FSB

QX6700 = 2.66GHz - 2x4MB L2 Cache - Unlocked - 1066 FSB

QX6800 = 2.93GHz - 2x4MB L2 Cache - Unlocked - 1066 FSB

QX6850 = 3.00GHz - 2x4MB L2 Cache - Unlocked - 1333 FSB


Different Chipsets and their features:




As we are obviously most interested in the way these different chipsets overclock, let me give a brief outline what each of them is capable of.


The 965P Express Chipset is known for high FSB, but it has problems with D9 memory and the stock BIOS. Flashing to a newer BIOS usually fixes this, as well as the no-OC problem with some NVIDIA cards. For example the 7600GS, if you have that, it might not let you OC 1 MHz, but there is a fix. Getting a cheap PCI vid card and OCing with that, then putting the PCI-e back in will work for most people. As seen abvove in the table, it supports CrossFire, however only in x16 and x4 configuration (x16 PCI-e slot for the master card and x4 PCI-e slot for the slave card). Sources can be found in Post #5.


The 975X Express Chipset is not a fan if high FSBs, most won't even get to 400MHz (DDR2-800). This would be a good choice for CPUs with higher multi's (i.e. E6600, E6700 and Core 2 Extreme Processors). Most 975X boards are paired with the IH7R southbridge, which provides less SATA ports, an ATA channel but no Ethernet. If you want to do some serious overclocking, the 965P, 680i or RD600 chipsets will do better than this.


The nForce 650i Ultra/SLI is a great choice for someone who upgrades their computer to a Core 2 Duo, wants to do some decent overclocking but also wants to keep all his/her PATA drives. Yes, thats right, this chipset provides 2 ATA ports, which is not found on other Core 2 supporting mainboards. I can't tell how this board does overclocking, as the only board that is using this chipset that is out is the ASUS P5N-E SLI at the moment.


The nForce 680i SLI is THE overclocking chipset for NVIDIA grafics solutions. Numerous reviews and reports state that they have reached speeds on these boards that only the RD600 can keep up. A member of a German Overclocking forum got his RAM running at DDR2-1300 on a 680i board, stable at DDR2-1260. On the contrary, boards with this chipset only offer 1 ATA port but 2 x16 PCI-e ports and an extra 8x PCI-e port for a PhysX card or a third graphics card.


The ATI RD600 is the top overclocker board for ATI based grafics solutions. WindWithMe on Xtremesystems has tested a sample of this board here. Overclocking wise, it seems that this chipset is capable of world record FSBs and high CPU clocks, but that depends on the manufacturer of the mainboard (only DFIs version available at this point). If you are hunting after the highest benchmark scores, this board is not so much for you, as [url="http://

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hey king, nice guide but the 965 doesn't officially support crossfire, there's an MSI board that supports it and ways of "hacking it" but it was released after intel pulled the plug on ATI


and is there any source on the fact that the 975x doesn't get higher clocks?????

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thanks inji!


@ Unforgivin, I have a 965P, and it OFFICIALLY supports CrossFire (says on the box at least ;)), only 16x and 4x (instead of 8x and 8x), but it supports it. During the research for this guide, I read 2 or 3 sources that stated that the newer 965P's supported it.


For the 975X I mainly read on XS and other overclocking forums, also some reviews stated that it is fast, but no good for high clocks.


[edit] source for CrossFire on 965P chipsets -->




those sources only say Gigabyte, but I'm sure that there is some sort of driver hack or something to get it working on the other manufacturers boards as well.

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the Asus p5w dh is not a bad board, the main problem people had with it @ XS was that they would hit a fsb wall around 360-370 and thus would be required to make the ram run in spd mode pretty much only overclocking the cpu and not the ram.

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