disclaimer : if u kill your CPU or any part of your pc by trying anything described below U are the only one responsible and dont have the right to get mad at me :P
This is also just a guideline as u might be using an older core 3500+ or even a motherboard that wont allow u to change every setting.
There are also faster ways to oc from windows ,but they dont allow u to adjust the multiplier,ram timings or ram divider ,so i prefer to Oc straight from the bios.
U will need a few software tools before u start;
First and foremost get Speedfan (
http://www.almico.com/sfdownload.php) so u can monitor your temps and voltages.
Aslo get CPU-Z (
http://www.cpuid.com/cpuz.php) so u can easily see at what speed your processor and memory runs
and Finally u should get Prime95 and use its torture test to check for stability issues ; let it run for about 15minutes and if it throws an error u should lower the OC(if u see no errors and temps stay low u can go higher), once u think u have a stable OC let it run a few hours and see it it stays errorfree.
Then on to the overclocking itself (and i hope u know how to do a CMOS-reset because u might well need it
)
Start by lowering your CPU multiplier from 11 to 7 orso. (do this so u can test the higest FSB your ram can handle without actually overclocking the CPU at first)
Then relax your ram timings (3-4-4-8 should work) plus set the Ram voltage to 2.8 and start upping your FSB in steps of 10mhz, do this untill Windows wont boot or till u get errors in prime95. once u get errors or it wont boot, lower the FSB by 5. If it's stable then up it by 2 till u find the higest FSB that still runs prime stable.
Once u have found the limits of your ram u can start on the CPU.
Set the Ram divider to 200 or 333mhz (instead of 400, this time so u only OC the processor and not the ram) and the CPU-multiplier to 11, then start at 220FSB orso and boot.
U SHOULD get into windows and see in CPU-Z that the CPU runs at 2420mhz
Run prime95 for 15minutes and see if its stable (and monitor your temps! ,i would aim to keep your CPU temp below 55°celcius under load)
if its totally stable AND doesnt run hot u can up the FSb by 10mhz ,if its unstable but not overheating u can try upping the voltage by 0.05v.
Do this untill u get prime errors or untill the temp under load ges too high. Then lower the FSB by 5mhz and try again (same as with the ram ,if it works go 2higher ,if it doesnt go 2 lower)
Once u know both the higest ram speeds and higest CPU speeds u can start matching them up.
Say your ram goes up to 260mhz and your CPU goes up to 2500mhz without overheating. Then try to boot at 260(fsb) x 9.5(multiplier) which will give a cpu speed of 2470mhz. (note that the ram divider would be back at 400mhz here)
If your ram only goes up to 220mhz and your cpu up to 2600 u wil have to set the ramdivider to 333mhz and run the CPU at 260 x 10. this will have your CPU running at 2596 mhz and the ram somewhere near 220.
Once u have found a stable final overclock u can try tightening the Ram latencies, lowering the RAM voltage and cpu voltage in small steps (all 1 by 1) till u get a stable CPU running at the lowest voltages and u get a tiny bit of extra performance out of the ram with tighter latencies.
Note that some boards wont like half multipliers (they might not boot ,or underclock your ram by themselves) ; some ram might not like booting in anything but their rated specs (so a CL2 stick might refuse to boot in cl3) and some procs clock better then others. So u will have to test yourself what the highest speeds u can reach are.
As an example my 3500+(venice core)with TCCD ram runs at 2800mhz (280x10) rockstable for 24/7 at 1.45v and ram timings of 3-4-4-7 under a Tunic tower 120. (whee FX-57 speeds for 95€ instead of 850€
) and temps are 35°idle ,42° load
Dont expect to reach 2800 mhz on a stock cooler ,but u should be able to reach +-2500mhz without much problems which is almost a 15% OC for free, which should be noticable in any benchmark and in LFS too
Hope this gets u started and u dont kill any hardware