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New Member
Dec 3, 2003
I am trying for the first time to overclock a PC, I have been reading these forums for some time now but am still unsure if what I am doing is right.

In my bios it lets me change stepping from I think 6 all the way 22. My fsb is 133 and my stepping 16 by CPU default. I can choose to change my fsb from 133 to 400.

Whenever I change my fsb it also ocs my ram which is ddr333. Is it possible to ONLY overclock the fsb so it is at the same speed as my ram?

What I really need is some advice as to whether my pc CAN be oced or if, as I am starting to feel, this CPU is already running about as high as it will go.

TY in advance.
Hi and welcome to the forums.
DDR 333 or PC2700 runs at dual 166 FSB default and is overclockable on average to 180s-190s FSB. Multiplier should be lowered or adjusted accordingly as you raise your FSB.

MHz speed = [FSB] x multiplier.

Resulting overclock will depend on things like cooling and power supply brand.

You have a 2600+ Thoroughbred B which does up to 2.3 GHz on average with choice components.

If you have an nForce2 mobo which has a PCI lock, you can raise the FSB no prob but if you do not, read this...

There is something called a PCI lock and nForce2s have it and VIA mobos do not.

Increasing the FSB changes the speed of the whole motherboard and everything connected to it unless the mobo has a PCI lock. PCI lock is good because it saves your other components from the negative effects of overclocking.

VIA mobos use a divider.

First of all FSB is more important than MHz.
MHz is FSB x multiplier but the idea is to have the highest FSB possible. Without a PCI lock, that may not be an option. This is why:
Lets’ say VIA mobo has a /4 divider for 133 FSB and up, then a /5 divider kicks in for 166 FSB and up.

That means 166 / 5 is about 33.2 default.
180 /5 = 36 and 190 /5=38.

38. That’s 15% out of specs your hard drive and sound cards and everything connected to the mobo is running out of specs.

You go further than that and you’ll be entering into hard drive scrambling territory... unless you have a PCI lock which nForce2 does and VIA does not.
No, it can go higher. I had two modded XP2600/266 CPUs running at 2.3 GHz (144 MHz FSB) in a duallie. They ran at 2.4 GHz (150 MHz FSB) but my HS/Fans couldn't keep them cool enough.

BTW, you can run the DDR asynchronously at a lower speed, but that has a negative impact on performance. IMO you should run the DDR at the FSB speed as high as it will go for best performance.
you could set your ram at 133, overclock and run your ram and fsb at the same speed OR set multi to 13 and fsb at 166 and still be running your ram and fsb at the same speed and start overclocking from there
OK thanks for the replies so far.

Coltice, are the differences between the 166 and 133 xp2600 purely the stepping and fsb changes. My mobo can take 166, so if I change fsb to 166 and lower the stepping it will be as easy as that? Would it make my ram run at 368 instead of 333 tho.

Sorry if this seems obvious to some, but im just starting my journey into ocing.
i don't know what motherboard you have but there's probally somewhere in your bios to set your rams speed 133/166/200 and so forth.if we knew what motherboard you have that will help.as far as the differences between the 2600's i think as long as they have a 256k l2 cache yes