need some advice for my E6600 overclocking..

Well, the DQ6 can reach >400Mhz FSB speeds pretty easily, so I'd say your overclock can definately be improved. Did you know there's a C2D overclocking guide on this forum? It gives step-by-step instructions to get the most out of your OC. Check there. Also, make sure you're running the latest MB bios, should be F4 for you, though F5 betas are also available. What heatsink/fan combo are you using? How are your temps at 3.4? 40/55C, while well within the thermal envelope for this cpu, is still a tad high. Also, are you running a ton of HDDs/fans in this system?

Well, something is obviously causing you to become unstable, let's see here.

1. The memory you listed should be fine for overclocking, so I don't think that's where the instability is coming from. Play with the timings and your ratios though.

2. The F4 bios is pretty darn stable from everything I've heard, maybe someone else has heard of conflicts with it?

3. Your heatsink/Fan. Ok, if I were you, and wanted a big overclock, I'd ditch the stock intel crap and get a good air cooler. Thermaltake typhoon, tuniq tower, something along those lines. It'll set you back roughly $50 regardless, but it's a darn good investment and will prolong the lifespan of your OC'd cpu, as well as helping to keep your in-case temps under control.

Basically, put your vDimm up to +0.4V, and play with your mem/fsb ratios. If it means slowing down your memory to get a bigger cpu OC, oh well, guess which will give you the bigger boost? You could try inching your vCore up .025 or .050 as well, but that'll increase your thermal dissipation, so I'd get the new HSF first.

now, after i followed all the way that both of you gave, i can run prime stable for a long time.. but, when i run super pi 32mb in the same time, my pc was display "blue screen" an restart after that..

this is my setting in bios :

fsb = 378x9
ram multiplier = 2
ram timing = 4-4-4-12
ram voltage = +0.45
MCH voltage = normal
FSB voltage = normal
vCore = 1.475

what i need to do..? i have replace my stock cooler with thermaltake big thyphoon..

1. do i need to set the ram timing to 5-5-5-15..?
2. if i up the vCore to 1.5v and above, my pc can't boot..

find the source of the issue - lower the ram speed and slacken the timings and see if thats the source of the issues

and yeah otherwise the stock cooling wont do miracles

I suppose there's isn't timing option in BIOS called 'tFRC' is there?
Set it to 'Optimal'.

i cannot find where is 'tFRC' in the bios..
memory performance enhance, normal@fast@turbo

ok.. now i can boot and log on windows..
after that i run the prime, and its stable..

then i run super pi 32mb in the same time, the error appear..

1st, "Not exact in round"..
after that i run super pi 32mb again, and "Not Convergent in SQR05"
what thats mean and what i need to do..?

this is my setting in bios..

fsb = 378x9
pci express freq = 100
memory multiplier = 2 (2 is the lowest in bios)
ram timing = 4-4-4-12
memory performance enhance = normal
dimm overvoltage control = +0.4v
MCH overvoltage control = +1.5v
FSB overvoltage control = normal
cpu voltage control = 1.475v

umm i could be wrong, but if the DQ6 is anything like its little brother the DS3 then PCI-E Frequency should be "Auto"

wusy would know for sure, if its supposed to be auto then thats prolly whats holding you back.

After reading the whole thread - I still think your memory is way out of spec... You are running with 675MHz CL4 memory at 756MHz CL4, and complaining you are getting errors... Change that memory to CL5!!!

Wusy told you about this in his guide already, see below...

When 1FSB:1RAM is overclocked above the rated frequency of your RAM use the following values
Timing: 5-5-5-15
vDIMM: 2.2V