Why 2 CPU Speeds? Better overclock?

I bought a system around a celeron 360 775 I had from a friend in hopes that I would later get a bigger proc. later. I got a UD3P and a HD4850 but had to trade up the celeron for this Pentium 4 @ 3.40GHz due to incompatability. But BIOS and CPUz lists its speed at 2.40 (which is 200x12). Windows reports it at 3.4GHz. After overclocking the FSB to 266x13 (which is 3.45GHz) Windows reports 4.52GHz (which is 266x17).

Secondly, I am trying to get more out my overclock, my results:

[FSB=200] [x12] [Vcore=1.35] stock
[FSB=266] [x12] [Vcore=1.35] stable
[FSB=270] [x12] [Vcore=1.35] BSOD on Win startup
[FSB=266] [x13] [Vcore=1.35] stable
[FSB=270] [x13] [Vcore=1.35] BSOD on Win startup
[FSB=270] [x13] [Vcore=1.45] BSOD on Win startup
[FSB=200] [x14] [Vcore=1.35] CMOS fails, must clear
[FSB=200] [x14] [Vcore=1.45] CMOS fails, must clear

I don't know anymore than to mess with the FSB and multiplier, the vcore does not seem to do anything and there are 3 cpu voltages (core, terminate, and reference (<1).
Any help from the experienced would be nice, even if it is to say don't f with this proc anymore. I am in the market for a Q6600/X3220 anyway.

This is my first overclock and don't know what to do from here.

Welcome to the forums

I would check to see if the motherboard supports a PCI lock to prevent overclocking the PCI/AGP Bus when the FSB is increased. I'm not exactly sure what's going on with windows but i'm inclined to trust CPU/Z and the bios over what windows says...

Which version of windows/Cpu-z are you running?
What type of cooling are you using for the processor?
What are the temps on the processor idle/full load?
What programs are you running to test for stability?
Can you give some more detailed specs of the system your running?

*edit*
One thing that I just thought about, if your processor is overheating then your processor might be running at a reduced speed. It's been a number of years since i worked with P4's but I remember my bios had a setting which when enabled would reduce the processor's frequency if it hit a target temperature. I do not think that windows was able to detect that speed reduction.

Forgive me if I miss some info:
Dual boot Win XP SP3 => Win 7; both fresh
CPUz v.1.45 May2008
Using EasyTune6 for Temps only
AVG scanning 4 directories to get 100% CPU temps
Arctic Freezer 7 cooling
Temps 35 CPU, 43 System Idle
Temps 47 CPU, 44 System at 100% AVG scanning 4 directories
Gigabyte EP45-UD3P BIOS v.FD 11/23/2009
Pentium 4 650 prescott
2x2Gb Crucial DDR2 800 CTVOS2GBD2S806C
XFX HD-485X-ZDFC Radeon HD 4850 1GB
No Optical
2x500Gb WD AAKS
1x160Gb System drive partitoned at 80Gb(1)XP-80Gb(2)W7


Forgive my use of the term 'stability' I say that to mean it boots up, runs my games and does not BSOD with general use.

Intel SpeedStep Technology (EIST) is what you are thinknig of, I read it earlier today on another post, supposed to lower multiplier from x17 to x14 if over 67.7C built into the Intel chip.

same problem with me too i wonder which is wrong the motherbroad or the processor
i hate with this situation