Overclocking guide: Part 2

Let's get started!
The first step is to enter your BIOS.  To do this, boot up your computer and while it begins to post hit the Delete key (it might be F1, F10, F12 or ESC too, try them)
The best way to start overclocking is by increasing your FSB by 10mhz at a time and running Orthos or SuperPi (both stability testing programs) and monitor temps, and increasing voltage when needed. The idea is that when you get an error or can not POST, you should up the vCore (CPU voltage), restart, boot up and run Orthos again.
For now, we'll focus on your RAM.
We are going to set the RAM to 1:1. As a result, the RAM will be running synchronous to the FSB. This might sound a little confusing but hang in with us for a while.
DDR is Double Data Rate, so when you look at the RAM divider settings in the BIOS, you will see that if the CPU frequency (the FSB) is set to 266MHz, the RAM will be set to 533MHz. This is what is known as 1:1.
Whatever the FSB, just double it to give you the RAM 1:1 value. So, 400 FSB would equal 800MHz RAM and so on.
When you're done with the RAM, do a 10% overclock on your FSB to jumpstart. So if it's set to 266, set it to about 290mhz. For now, leave the vCore to auto.

Boot into Windows
Now save your settings, exit the BIOS and start windows. Download CPU-Z if you don't have it already and check your new CPU speed. Admire it and feel proud. Now let's get into some serious overclocking!
We want to have Core Temp and TAT (Intel Thermal Analysis Tool) open (or one of those two plus the temp monitoring software of your choice). The reason for using two different temperature-monitoring programs is that it increases the likelihood of getting accurate readings - and we want to be keeping a very close eye on the temperatures.
Open Orthos, select the Blend test (Blend - stress CPU and RAM) and set it going. Your temperatures will now rise as both of the CPU's cores are under heavy load. This is normal and is exactly what we want - we're trying to quickly establish if there are any temperature-related problems.
Leave Orthos running but keep a good eye out for the temperatures.
This is a relatively modest overclock so, hopefully, the temperatures will be under 65 deg C - well under, in fact.
So, restart and get back into the BIOS. Keep in mind that as you up the FSB, the motherboard will automatically up the CPU voltage (vCore) if it is set to AUTO, so it is important that you keep an eye on the temps once you are running Orthos.
Increase your FSB in 10 mhz at a time and if you can't POST, try 5 mhz increases until you can boot into Windows without errors and always do an Orthos run to check for stability.
You may find that you get to a point where it is stable but the temperatures are a bit too high for 24/7 use. In that case, it is best to keep lowering the FSB until you find a point where you are happy with the temperatures and the performance.

Tweak and tighten that memory
In this part we will be looking at tweaking voltages and tightening memory timings and generally optimising your PC now it is overclocked.
At this point, as we are going a little bit more advanced, we have to assume that you've read the other parts of the guide, have got to grips with how things work and know how to recover if you stuff up and end up with a bad overclock

Disclaimer - please read this bit, it is very important!
RAM is potentially the easiest component in a PC to kill. Applying more voltage than standard carries a high risk of damage and/or failure. All overclocking is done at your own risk.
A lot of RAM just will not overclock much, no matter how much voltage you feed it, so if things aren't working out for you in this part of the guide, leave it right there, rather than throwing more voltage at it.

Tightening up those timings
Now you have a nice, stable, fairly large overclock, we can look at tightening the RAM timings.
At this stage, be prepared for some CMOS clearing, blue screens of death and general odd behaviour from your PC - but it should be worth the hassle!
If your RAM is already running tight timings, such as 3-4-3-8, then there is no great need for you to follow this part, you can skip to the voltage-tweaking part further down.
If you have some RAM that uses Micron D9xxx chips, you will probably have more success than people that aren't. The Micron D9 chips can often do really insanely-tight timings at quite high speeds but will likely require a good slug of voltage to get there.
Some sticks are rated for up to 2.45V but, for that kind of RAM, you need active cooling - a fan that's blowing directly onto the RAM to dissipate the heat that's generated.
It's pretty simple, the higher the voltage, the hotter the sticks will get and the hotter they get, the more chance you have of getting errors or even killing the RAM outright, so you need active cooling
An 80mm or 92mm fan blowing at a moderate speed from a couple of inches away is enough to keep most D9 RAM happy, whereas a 120mm fan can have too big a dead spot to do the job as well.
There are also dedicated RAM coolers that you can buy from the likes of OCZ and Corsair and some of these work well.
As a general rule of thumb, if RAM is 2.0V or over, blow a fan on it. Better safe than sorry - keep the RAM cool.
OK, back to the timings.
Some applications benefit greatly from tightened timings, other don't, all you need to do is find a memory-hungry program that you use a lot and try tightening your timings. If you can see a benefit, then great, if not, change them back and forget about them.
Install the free, lite version of SiSoft Sandra, currently at version XII (2008). This has a very useful memory bandwidth benchmark. Run it and make a note of your current memory bandwidth.
Doing this on our testbed PC revealed that the RAM is rated for 5-5-5-12 @ 1066MHz (PC2-8500)
This will often mean that if it were to run at less than the rated 1066MHz, say at 800MHz, we could then tighten the timings without having to up the voltage (not always, but more often than not).
So, let's go into the BIOS and look at the existing settings. The FSB is 380MHz and the RAM is running at 760MHz with timings of 5-5-5-12.
Now, we happen to know that the RAM will go higher at those timings, so, in theory, can go tighter at a lower MHz. So, we'll change the timings from 5-5-5-12 to 4-4-4-12 and see what happens.

Voltage tweaking
So, your PC is rock-solid stable but there's an awful lot of hot air coming from the exhaust fan. What can you do?
Well, this section is for those of you who want to keep their overclock but would prefer to reduce the heat output just a little.
This involves little more than common sense and a process of elimination.
First, anything voltage-related that's set to Auto, simply change manually to its lowest value.
Do this one item at a time, test for stability and then do another. Otherwise, if you adjust a few things together and the system turns out to be unstable, you'd have to guess which of the changes is causing the problem.
A boost to Vcore is probably the biggest source of heat increase. But, unfortunately, when you overclock, you will generate extra heat, even if you don't add extra voltage. Nonetheless, you can try to reduce the amount of Vcore that you use.
Simply drop the Vcore to whatever you think and then test with Orthos/Prime/SP2004. If the PC fails, then more Vcore is needed, simple as that, so try upping the Vcore in single notches until stable again.
You can always back off the FSB but that kind of defeats the object of all the hard work we've just done.
There's a trade off between temperatures and performance and you're the only person who can decide what's best for you.

Happy overclocking!