because you dont want to set ur vcore too low for idle or you wont even boot into os, or hang the in os due due lack of juice (idle mode)

ya, that is why i was    when most "tech-enthusiast" OC their pc and doing 24/7 BT with minimum stuff 

well, ur guide is well documented, but it lacks examples and pictures, some newbies may get confused.

Advance overclocking – BIOS OC but windows running C&Q!

Facts about this guide
- Overclock 24/7 in BIOS (C&Q disabled) but able to run C&Q in windows!
- For advance overclockers, as this method can DAMAGE your rig if you don’t know what you’re doing!!!

In fact the guides are wrong.CnQ can be enabled when we overclock CPU even in the BIOS

IMHO, advanced overclocking can be divided into at least 2 categories:
1. extreme overclocking which will reduce the lifespan significantly.
2. optimized overclocking which will has a balance of speed, lifespan and power.

If you are considering only option [2] in this guide, the most important thing is cpu Vcore. At best, tweaking and tuning MUST be done only at stock voltage, and BIOS overclocking is always the BEST approach.

However, when I upgraded to X2 4200+, I found that anything above 2530 Mhz would cause my rig to hang if C&Q is enabled.
And imaging your CPU suddenly going from load 2.9Ghz 1.5v to 1.0Ghz 1.1v or vice versa. Might put a huge strain on the CPU???

His point is, manual C&Q, where user control the raw power at will
using bios/auto C&Q may make ur proc speed/multi jump up and down controlled by OS

No, it won't strain the CPU at all, and it will not go to 1.0GHz. The lowest clock speed you can get is 5xHTT.
The reason why you get hang in C&Q beyond 2530MHz is because ur idle CPU clock speed cannot run at 1.1V.

Hello, I'm pretty new to overclocking and already understand most aspects of it by reading the posts and google, but what have been confusing me are the FSB and MCH voltages.

Can someone please explain to me how will I know if I need to increase them?

For example, say I overclock an e6400 to 3.2 ghz (400 mhz) with 1.35 vcore, I run some tests (orthos, small ffts) and it fails.

I've run memtest on my memory with the timings I want overnight at 800 mhz and there were no errors.

Now what I know so far is that here is where I up my vcore and try again, until I get it stable without failing orthos.

So my question is :

1) When exactly do I need to up my FSB or MCH voltages? How will I know? Or is it just guess work?
It is a guess work... increasing MCH voltage is needed if overclocking on INTEL chipset board.... normally oc more than 3ghz MCH must be increase to gain stable pc else u will love to see BSOD.

2) Will upping my FSB or MCH allow me to run at a lower vcore ? Or it does not work that way?
No way.. CPU and Chipset Core is not working that way... want a fast car running more speed and want to save petrol? =x
unless the car itself can running faster with low vcore then it is fine.. consider lucky you

3) If yes, FSB/MCH voltage vs. Vcore, which one is the better one to decrease/increase in terms of being safer, more stable, long term usage, etc. (i.e +0.1V on FSB is better than having to increase +0.05V on Vcore, something like that, if it works that way anyway)
Wanna overclock make sure cpu heatsink is not original and better cooling...
good pure power supply is needed and if it is intel it is MORE needed a better power supply if wanna clock...
no body can know how my cpu need how much vcore to gain how much overclock i can...
at first clock cpu until u think it is fine with good prime 24 hours... stable...
when gaming or something else pc hang .... that might cause mch have not enough power.... so increasing it will helps to gain stable system... easy word ( if original 1.20 u need up 1.40 something)
so u need more reading on that topic...read more is the key ..
some ppl like to try give cpu more fsb 1st and increase vcore with it slowly...
some like direct give a power vcore shot and gain top cpu speed .... then drop down vcore slowly and prime it... stability test... ( that is me too ) so need make sure u have good cooling ...

That's what i know

Will really appreciate it if someone can answer these questions 

Thanks in advance