Please do not reply (yet) guide in progress

[Nickel020]

Overclocking basics is still in progress, the first revision of the Temperature FAQ is done though!

Let me know what you think!


Core 2 Overclocking basics


DISCLAIMER: I will not be held responsible for any damages that may incur from overclocking! Everything you do is at your own risk!
Also back up all important data before you overlock. Data corruption is very unlikely but it may happen if your motherboard decides to die or something else goes very wrong!


Introduction

The most basic thing that you need to know is that you increase the FSB to increase the CPU speed. RAM speed is linked to the FSB by a factor that is adjustable so you will need adjust that factor as well. Additionally, you will need to increase voltages.
Overclocking is largely a trial and error routine. You try to figure out how fast each of your parts (i.e. RAM and CPU) can run on its own by trying different settings and then try to combine the fastest settings for both.


If you don’t know what the FSB, the multiplier and effective and real FSB and RAM speeds are or unsure if you know it all continue here, otherwise skip it and continue with post #2


Let’s start with definitions of the settings that you need to change.


The CPU speed is derived from the FSB multiplied by…. the multiplier!


FSB (Front Side Bus): The connection of the CPU to the northbridge*, usually 200, 266 or 333 MHz for current Intel Core 2 CPUs. As four bits of data are transferred every clock cycle (i.e. every Mhz), Intel markets these as 800, 1066 and 1333 respectively because of that. These higher frequencies are also often referred to as the effective FSB.
The FSB can be adjusted upwards and downwards and is only limited by how much the motherboard and CPU are capable off.
* chip on your mainboard connecting the CPU to everything else, a higher FSB means more bandwidth and is therefore better for performance

Multiplier: This is locked and can only be decreased but not increased to a setting higher than the stock value. The difference between an E8400 and an E8600 CPU for example is the stock multiplier of 9 for the E8400 (resulting in 333 x9 = 3.0GHz) and 10 for the E8600 ( 333 x10 = 3.33GHz)
Because the multiplier is locked on all CPUs but the Extreme Edition CPUs you can only overclock your CPU by increasing the FSB.
The multiplier is called "CPU Clock Ratio" on Gigabyte mainboards and “CPU ratio setting” on Asus boards.

RAM: DDR RAM (no matter whether DDR1, DDR2 or DDR3) actually runs at half the speed it’s quoted at (i.e. 333 MHz for DDR2 667, 400 MHz for DDR2 800, 533 MHz for DDR2 1066 etc.). As it transfers two bits of data per clockcycle these higher effective frequencies are commonly used though.
RAM is backwards compatible, meaning that you can always run faster RAM at a slower speed (e.g. 1066 RAM at 800 or lower) but also faster, RAM can be overclocked like the CPU itself.

[Nickel020]

Relationship between RAM and FSB speed
The important thing about RAM when overclocking is that it needs to be able to run at least as fast as the speed of your FSB (I’m talking about the real MHz, not the effective values). So if you want to overclock your E8400 to 4.5 GHz (500 x9 = 4.5GHz which would be high but is possible) you would need RAM capable of running at 500 MHz (DDR2 1000) so you should get DDR2 1000 or better RAM.
You can also run RAM at a higher speed than the FSB, there’s a setting called “system memory multiplier” on Gigabyte boards in the BIOS for that. If you have a FSB 333 MHz CPU (1333 quad-pumped) and DDR2 800 (400 MHz) your BIOS will likely automatically cause it to run at DDR2 800 which is the 2.4 system memory multiplier (333 x 2.4 = 800). If you increase the FSB to 400 now, RAM speed will also increase to 400 x 2.4 = 960! To prevent that you can change the system memory multiplier to 2.0 and have the RAM running at DDR2 800. Remember to alwys check the system memory multiplier when changing the FSB!

The A, B, C, D at the end of the system memory multiplier indicate at which FSB the multipliers should be used. Always take the one closest to your FSB, rounding up.
On Asus board the setting works a little differently. It’s called “DRAM Frequency” and doesn’t show you the multiplier but lets you cycle through different multipliers and shows you the resulting RAM speed. If you change the FSB, the RAM speed will change!

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Temperature FAQ

In this little FAQ I’m trying to answer the most common questions people have regarding their PC temperatures.
The first thing you should know is that it matters very much which program you use! The manufacturer’s own program (i.e. Easytune for Gigabyte) usually shows wrong temperatures, and so does the widely used SpeedFan most of the time unfortunately.
To get accurate readings of your CPU temperature you should use Core Temp or Real Temp in their newest versions.
Download Core Temp:
Core Temp
Download Real Temp:
Real Temp - CPU temperature monitoring
Everest Ultimate also correctly reads the CPU Temp and is able to read other sensors as well.
Lavalys - Comprehensive IT Security and Management

Help! Is my CPU temperature too high?

In 99% of the cases the answer is simple: No it’s not so high that it will damage your CPU! If you look at Core Temp or Real Temp you will notice a value called TjMax which usually lies between 85C and 105C depending on the CPU model. This is the maximum temperature that Intel allows their CPUs to reach, after this value the CPU will throttle to prevent a further increase in temperature which may damage the CPU. Yes, Intel thinks that your CPU will not be damaged as long as your CPU stays below TjMax!
Many people will tell you that a CPU Temp over 60C or 65C for example, but that is just their opinion! This stems from overclockers trying to keep their CPUs as cool as possible and 60C is a value that good coolers can achieve. Since instability is more likely at higher temperatures this is not a bad goal, but not the whole truth either. An overlock that is 100% stable at a load temperature of 55C may crash the system pretty quickly at 65C.

So how hot should I allow my CPU to get?
The answer to this is also simple: Never so hot that the system becomes unstable! I prefer to keep my system below 75C, but that is again just an opinion! High temperatures may over time cause damage, but that is very hard to prove and a debated topic. If you want so be sure this does not happen, my recommendation is to stay below 65C.

Other temperatures
Chipsets and GPUs are usually allowed to reach temperatures over 100C and many high-end GPUs operate perfectly with temperatures around 90C for years!
The important thing is again that "too high" is defined by whether the temperature causes instability or not!
If you think your chipset is getting too hot and causing instability there’s a simple test: Take an extra fan and direct it at the chipset heatsink. If that solves the stability problem, then the temperature actually was too high. If it doesn’t, the chipset temperature obviously wasn’t the problem since the chipset is much cooler with a fan directed at it.

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[Nickel020]

Looks like TweakTown doesn't allow topic editing :( I'll ask a mod to edit the topic title...

[acostarm]

Thank you for your work! In particular your aticles on Tempature FAQ and the Memory comparison were very informative. Keep up the great work!