First you must know some basics about how a motherboard works . It has a clock that puts out a certain frequency. This value is multiplied by certain numbers, and gives the Front Side Bus (FSB) frequency, Random Access Memory (RAM) bus frequency, Peripheral Component Interconnect (PCI) frequency and Advanced Graphics Port (AGP) frequency.

The FSB is not the same thing as RAM bus frequency. Also, the RAM and FSB frequencies are different from the actual speed, which is twice as fast, because they are working at double data rate (DDR).

For example. 266 FSB runs at 133 mhz.

All the speeds on the mother board depend on it's clock speed.

The CPU has three important values: it's FSB, multiplier and core voltage. The actual speed of the CPU is FSB frequency times the multiplier.

For example: XP1600+ has a 10.5 multiplier value and 133 FSB, so in theory it runs at 1400mhz .

You will need a good motherboard that has the option to set the FSB speed, multiplier, core voltage , RAM voltage and RAM latency.

Most AMD chips come multiplier-locked, which means you can't change the multiplier settings, so you have to unlock them. There are many guides and programs to unlock your chip on the internet, search for one for your specific chip.

Make sure that the CPU is set at the same bus speed as the RAM so that one of the two may use the others left-over bandwidth.

For example: If you have PC2700 memory and a 166mhz RAM capable motherboard you should set the CPU to 166 mhz FSB.

Lower the multiplier value below the default value until you are around 20% below the default.

Now start increasing the FSB keeping the low multiplier. The purpose of this is to keep the FSB stable, no matter what speed the CPU is at. To gain stability at high speeds you must increase the voltage to the CPU and to the RAM, sometimes even to the AGP slot. This is very tricky because voltage brings stability, but also heat.

You need a really good cooling setup so you dont fry your chip. Try to keep your CPU under 50 C if possible and no higher than 60 C.

When you hit the highest stable FSB, you can start to tweak the CPU multiplier. Increase it in 0.5 increments, until you have the highest possible stable speed. The CPU core voltage increase will help you stabilize this again.

Always keep an eye on your CPU temperature and never let it above 60 C.

Good Luck

Nice post and its really informative. I was planning on doing this to my CPU and was looking for a quality guide. Thanks this helped.

I was just wondering, does this work on a pentium 4? Its a 1.8 ghz processor and I'd like to try. If not, do you know how to make a p4 work with overclocking? Thanks
Aaron

You might have a great processor to overclock there my friend if your lucky. If it's a P4 1.8a then it's built of the Northwood core meaning that instead of the 400Mhz bus that it's underclocked to, it's acctually built on a 533Mhz bus effectivly giving a 50% performance increase to 2.4Ghz. The beauty of this is because that's the speed those processors were meant to run at and on that bus it produces almost no extra heat, and the dangers unsually inherint in overclocking are all but non-existent, all the with one little change in the bios. I specifically bought that proc for my last computer for that reason, though some won't do it as well mine set itself to 2.4 the first time I booted it up, so hope you have yourself one of those.

So why would Intel delibraly underclock a CPU sooo much if there is nothing wrong with it at full speed ? sounds like commercial suicide to me ???

Not going to try it with my Prescott P4 3.0 Ghz CPU (yet).... It needs a €35 cooler to keep it under 50 C .... The boxed one ranges around 60.

Maybe when I get another one, I'll try OC'ing too...

If you underclock, the power usage and temperature drops.. That way Intel can market with that, since they're CPU's are notorious for their extreme high temps (especially the high speed ones)...

Processors are sold on their performance.
ive never seen a ampage or average operating tempreture on a cpu advertisement.

so it seems unlikely that the cpu is just as safe and stable overclocked.

better fans can help with heat, but what about EMI ?

This is odd... I overclocked it and got it (p4 1.8 ghz) running @ 2.98ghz (!). Temp is stable @ about 45 celsius, and all is well, but my sound refuses to work. It says another program is using it and it just rebooted on its own. I reset the defaults and it works now, but I want it overclocked with sound. Is this a voltage problem? It was running fine with standard, save the sound problem. Please help!

I think I was overclocking my soundcard too much, but I have an abit motherboard with an AC'97 built in! I slowed it down so the increase was only to 1.98, but sound was choppy, but I had sound. Is there any way to fix this? Please help, I would like ut2004 to run a little more smoothly
Thanks
Aaron

Run Ut2004 with the "-nosound" parameter.
this will show how much of a loss of performance the sound is causing...

not even noticable, mabe a frame per second here and there.

fior gameing performance, you need CPU and Graphics card power.

turn off detailed textures in the graphics section, this doubled my frame rate, and you can only tell the difference when you stop, and face a wall at point blank range... not somthing you do much in 1st person shooters.