Here's an easy, step by step guide for overclocking, all you'll need is to download CPU-z and memtest86 (easy to find online).
and here's a guide that has helpful bios images to guide you.
The Process/Theory of OVERCLOCKING!
You should check out this thread to see what kind of overclocks to expect, and what core you have (if you don't already know).
CPU Speed = FSB x The Multiplier. Note: that a system clocked at 210 x 10 = 2100mhz will perform better than the same system clocked at 200 x 10.5 = 2100mhz. This is because your FSB affects not only your CPU, but your motherboard, and memory as well. But because you're also overclocking your motherboard and memory, these components can limit your max FSB. Your motherboard may be able to run at 220mhz FSB, but if your memory can only run at 200mhz, then that's where you're FSB overclock is going to have to stop (unless you buy better RAM). It is also possible that your motherboard will stop you before anything else does. When overclocking hardware for the first time, it's a good idea to find out how fast each component can run individually. Due to concerns w/ the PCI bus, sometimes this can be a bigger challenge for those w/ out a nForceII chipset. If you do not find your max overclock for each component, when you hit a wall, it will be harder to deduce what is holding you back. Here is the general process of overclocking your CPU/mobo/memory. The options you have in your BIOS totally depends on your chipset, motherboard make/model, and sometime your BIOS version. Your options may just be named differently or you may not have them. It's up to you to learn how to use your BIOS. Use google and/or your manual to figure out how. If you don't have the options you want... buy a new mobo.
Finding the max FSB for your motherboard:
1) Insure you have good or sufficient cooling for your CPU!
2) Boot into your BIOS settings.
3) Lower your multiplier to a low setting (5-8).
4) Raise your memory timings, and/or change your CPU/memory ratio so that your memory's FSB is always at/below it's rated speed. This should insure that your memory won't be limiting your FSB, just your mobo.
5) Disable useless BIOS features (depends on your mobo, but CPU speed spectrum, throttling are common ones).
6) Increase your mobo's voltage (vdd) as high as you safely can. Most motherboards don't allow you to increase your vdd more than is safe (1.6v-1.7v or higher w/ a decent northbridge heatsink). When in doubt search Google.
7) Increase your system FSB to 10-15mhz above it's rated speed. Always make sure your PCI bus speed isn't too high before you SAVE and exit your BIOS.
8) Then see if you can boot into your operating system. If your computer boots into your OS, and doesn't restart, or lock-up, increase the FSB by another 10-15mhz.
9) Continue until your computer reboots unexpectedly, or locks-up. When this happens go back into your BIOS and lower your FSB by maybe 5mhz and try again (if that doesn't work, lower it some more).
10) If you tried a FSB high enough, you may not be able to get back into your BIOS to lower your settings. In this case, you have to use the jumper located near the battery and CMOS chip of your motherboard. Move the jumper from its current pins, to the only other possible position. Then after about 5 seconds, move it back to it's original location. If you don't have one of these jumpers, take out your battery for 1 hour or so and then put it back in. You will now be back at default settings. So you must reset everything to where you were just before you hit trouble.
11) Once you are back into your OS open prime95 (which you have already downloaded and installed from here). Then start the "torture test." This will test your system for stability. Since we're only testing out the mobo, once torture test has ran continuously for 4 hours with zero errors/reboots/lock-ups, your FSB is stable. If you get an error or crash, lower your FSB by 1mhz or 2mhz. When running the torture test, check your CPU's temperature. It shouldn't be above 45C MAX since you lowered your multiplier and is probably running below stock clock speed. As mentioned earlier use a program like MotherBoard Monitor to monitor your uhh... motherboard.
12) You now know and can now write down your motherboard's max FSB
Finding your memory's max FSB:
1) Go back into your BIOS.
2) Change your CPU/memory ratio to 1:1 (A.K.A.: 1, 1/1, 3/3. 4/4, 5/5, etc).
3) Increase your memory voltage to the max your willing to run it at (SAFE: 2.7v; MAX: 3.1v).
4) Adjust your memory timings to 2.0-2-2-6 (The last value is up to you. 5-8 should be good, but many nforceII motherboards run better when the last value is 11).
5) First, try your memory's stock FSB. You should try your stock speed first because 2.0-2-2-x might be lower than your memory's recommended timings. Then continue to find your memory's max FSB just like you did w/ the mobo. Now if you work your way back up to your mobo's max FSB, and your system is stable, then you know your memory can do a higher FSB than your mobo; but you won't be able to find out what that is with out a higher clocking mobo.
6) The best memory stability testing program is Memtest86. You should unzip the downloaded file to a floppy/CD, then boot to that floppy/CD in order to start the test. Prime95 will also test your memory. Use both if you wish.
7) Now you have found your memory's max FSB w/ the memory timings 2.0-2-2-x. Test your bandwidth using SiSoftware Sandra's "Memory Bandwidth Benchmark." Depending on a lot of factors, you may have better overall performance w/ the timings 2.0-3-3-x. (or higher). You should definitely be able to reach a higher FSB w/ these timings than you did w/ 2.0-2-2-x. So set your memory timings to 2.0-3-3 and test some more! Once you find this max FSB, test your bandwidth again w/ SiSoftware Sandra, and see which settings yielded the higher score. You can continue to test 2.0-3-2-x, 2.0-2-3-x and whatever other timings you want, or settle on using the one you have already found to work the best thus far.
Finding your max CPU clock speed:
Before we continue, I must say that the important thing is to find the best multi and FSB combination, not necessarily the highest CPU clock speed. Though it is nice to know what the max clock speed is for your chip/cooling. The best combo will depending on which program(s) you want your system to run better on. For your final overclock settings you want your FSB and CPU clock speed to be as close to their maximums as possible. A system running at 230mhz x 10 = 2300mhz might perform similar to the same system at 210mhz x 11.5 = 2415mhz. You lost 20mhz FSB but gained 115mhz clock speed. Which one is better depends on whether you're running a CPU intensive application or a "system" intensive application. This is similar to when we found the best memory timing and memory FSB combination. To find out which combo works better: Use a program to benchmark your system such as 3DMark01 SE, or playing a game while monitoring your frames per second (FPS). Note: the following instructions assume you have found your mobo and memory max FSB. To get started w/ the CPU:
1) Enter your BIOS yet again. Set your FSB to something around 40mhz below your mobo's/memory's max FSB.
2) Go into the "monitoring" section of your BIOS. See what the vcc/vcore reading is when your vcc voltage is set to "auto." Depending on the quality of your power supply, the reading may be slightly under what it's suppose to be. But from this reading you should be able to tell your stock voltage.
3) You can then either first find your max overclock w/ stock voltage, or you can up your voltage right away to find your max stable clock speed for that given voltage. When overclocking you should never allow your CPU to get above 55C (not above 48C is better), nor increase your voltage by more than 25% from its normal voltage (when using air cooling). Feel free to play around w/ higher voltages (25%-32%) for very short term usage. But for daily use, 25% is pushing it.
4) After deciding/setting your voltage, increase your multiplier one setting. Save and exit BIOS.
5) See if you can boot into your OS. If so, continue increasing the multi by one setting, until you cannot get into your OS. Once you can't, lower the multi back a setting. Then run Prime95's torture test. If you get an error/crash while Prime95ing lower your FSB some and try again. If you pass for 12hours or more, increase your FSB. You should now be close to your maximum clock speed. Now to consider your overclock 100% stable, you should be able to run the torture test w/ out any errors/reboots/lock-ups for 12-24hours.
6) Now find your best FSB/multiplier combination and your set! Congrats on the overclock! Now go upgrade whatever is slowing you down, and do it again! The nice thing about finding all your max speeds is that if you upgrade say your memory, you already know what your motherboard and CPU can do.