Motherboard: EVGA 750i SLI
RAM: OCz ddr 1066 4gb (2x2gb)

I've been trying to overclock my cpu but once i put it past 2.7Ghz it becomes unstable and crashes.
Any suggestions would be helpful!

we're gonna need more info like what voltages ur using, cooling, temps, etc. we'll get it figured out.

Running the cpu on auto for voltage which is 1.3v
Memory is at 1.9v

using a Rosewill RCX-Z4 120mm 2 Ball CPU Cooler. air cooling.
I know temp isn't the problem because its running at 39 - 41 degrees c.

I just updated the BIOS to the most recent version.

Pcie is at 100mhz.

no clue. the pc will start and freeze after 10-20 seconds if it is anything past 1199 mhz FSB.

make sure your multiplier is set to 9.

yep it's set to 9x. I'm really dissapointed in this board. the bios update even said improves stability with kentsfield processors and there is no change whatsoever. i've tried pretty much every voltage between 1.3-1.4v and everything is the same. I'm really clueless now.

Try 2.0 or 2.1V on the memory.

i've tried 2.1v with no results. i'll try 2.0v and see what happens.

my memory timings are at 5-5-5-15 should i don't know if i should change them or leave them for now.

They should be fine, especially at 2.1V.

fairly certain its your motherboard holding you back. take the cpu up to 1.4v to compensate for vdroop (1.5v is max according to intel) try 8x333, and bump voltages up on everything just a bit. Then keep stepping up the fsb til you get to 400 or crash.

oh, and run your memory 1:1 for now til you get it to clock where you want it.

okay i just set it to 8x333 like you said and now it won't even boot at all. Its totally ****. i can't even get to the bios. i have no clue how to fix it now. awesome.

The first thing you should learn about overclocking is what to do when it goes wrong. Easy fix. Get out your manual and look for the instructions for the CMOS clear/reset jumper and move it so that it is in the reset position. Leave it for around 10 seconds then move it back. The manual should tell you exactly what to do. Make sure you disconnect power too. It's pretty simple as long as nothing blocks access to the jumper cap like it does for me Get used to doing it, this sort of thing happens alot when OCing.

yeah luckily my board has an easy cmos reset. just a button. like you said easy fix. anyway yeah i doubt my board is going to let me get past 2.7 Ghz even though it advertises it as a great board for OC'ing. I don't know what else i can do i've tried everything it seems.

Should still be able to do better than that even with a poor board. There's probably one BIOS setting causing you problems, that's how it often is.

What is your approach to OC ??
How you are getting 2.7
What is your FSB and Multy. ???
It's a bios setting issue
leave everything on AUTO and start pushing FSB Frequency
Could be Memory/FSB sync. problem
Memomory can work with different DRAM/FSB ratios
1:1, 6:5, 5:4, 4:3, 3:2, 8:5, 5:3, and 2:1
depends on your mobo and bios
1066 RAM can work with Q6600 at following DRAM/FSB ratios
2:1, 4:3, 8:5

push your FSB to 400 and set Mutyplier to 8, You'll get 3.2GHz (Leave FSB strap on auto)
and keep votages and other settings to AUTO
If failed set your ratio to 4:3 while keeping your voltages to autoand see
IF things work you can start reducing voltages if too high till you loose stability then go back to prvious stable value
You can also try FSB frequency 333 and Multy. 9 you'll get 3 GHz
In this case you can use Ratio 8:5

It could be your bios version. I was trying for ages to get my q6600 over 3ghz but the max I could get was 2.8ghz no matter what I did (I have a striker extreme by the way). Then after alot of searching on the net, I found out that the best bios to use for overclocking on my mobo was 1303. So I changed to that from 1305 and now I've got over 3ghz easy.
For some reason though, when I go over 3.2ghz it looks like it doesnt load the graphics drivers in windows because it starts in a low resolution, but im working on it, I only got it over 3ghz yesterday

i have been using multiplier 9x and trying anything between FSB 300-333 with no stability. It's probably my RAM i'm guessing.

so i should downclock my RAM from 1066 to 667? if i were to use ratio 8:5. That's what i got out of that chart.

i put the FSB at 400mhz and multiplier to 8x with no stability. It just freezes.

try running your ram unlinked , it could also be your psu, i have the same mobo
and proc and can get to 3.6 on air just make sure you have a good psu
and keep all your voltages in the green area for that bios,setting to auto will put you in the red in most cases(for that bios)

i've always run the ram unlinked.

I'm using a Rosewill RP600V2-S-SL 600W SLI Ready-ATX12V V2.01 PSU

what are your voltage settings??

vcore at 1.4,the rest on auto but if in the red i just go to the highest green setting, also some fsb numbers hit dead areas on your mobo,like you might be able to get stable at 1425(3.2ghz) but not 1250(2.8ghz)
sometimes the mobo just wont let certain numbers work ive heard it called dead areas on the fsb