Ok, here's my awesome overclocking guide with pictures and stuff. You may want to print this out hehe
To start off with, you need to download some tools for monitoring and stress testing.
There's a lot out there but I like to use Orthos
http://sp2004.fre3.com/beta/beta2.htm Because it will let you know if your cpu isn't stable without your whole computer shutting down. Usually people will run this overnight but you will usually see it fail in the first 5-10minutes if your cpu is actually not stable.
The other program is coretemp
http://www.majorgeeks.com/Core_Temp_d5665.html Which is used to monitor the temperature of each core of the cpu. It's usually a lot more accurate than software that comes with the motherboard because it monitors the temps directly from the cpu heat sensors not the motherboard ones.
You can also get cpuz to show things different informations about your system etc
http://www.cpuid.com/cpuz.phpOnce you have all that, you can reboot and head into the bios.
With the new Gigabyte boards you have to unlock the area to set your memory timings manually and you do that by pressing ctrl+F1 in that main menu of the bios screen.
You can then go into the M.I.T menu at the bottom and you'll see a tonne of crap, this is where you overlock
The first option, I've just left it on auto cause to be honest I don't know if it really does anything lol.
To start overclocking though you need to enable the CPU host clock control
By default it should be 266 for the e6600 because 266.66 x 4 (DDR quadpumping) that is where you get your 1066mhz FSB from and overclocking is done by changing the FSB (or clock multiplyer if it is unlocked but in your case it isn't, although you can change it downwards but not up)
You can see that I've already changed mine up to 333, this will overclock my humble e6420 from 2.1something to 2.66Ghz. If you want start by setting yours to 333 that will overclock your cpu to 3ghz (of course you can go higher later on
)
So the way that work is 9 x 333 = 3Ghz where 9 is the clock multiplier and 333 is the FSB (or value that controls the FSB the real FSB will now actually be 1333 instead of 1066)
Changing the value of the CPU host frequency is the basic step to overclocking, when you increase it you will notice another value also change, that being the memory speed. The memory speed is controlled by the Memory Multiplier and that is usually controlled by the SPD which is the information on the RAM itself that tells the motherboard what it's default speeds are. You can change these values though and you will mostly likely need to in order to get a stable memory speed.
The memory should be default as 800 however I'm using 667 but it actually runs at 800mhz fine with timings of 5-5-5-15 (worry about this soon)
You might notice that I've changed the ratio already from 4 (default ratio) to 2.4
If you leave it at 4, when you start increasing the FSB the memory speed will become too high for it to run (1333mhz). DDR800 can't run that fast though so you need to change the ratio down in order to keep the memory speed in a stable range. This is something you will need to kinda experiment with but try just making it a value close to your default memory speed for starters like 2.4 this should give you exactly 800mhz (333x2.4)
DDR800 can clock higher than 800mhz though depending on how good your ram is. It might be able to reach 900mhz higher.
One thing you will now need to do is tweak your memory timings.
Depending on what the timings are for your ram, usually they're written on the sticks somewhere but you will want to find out what they are and set them properly in the following 4 options.
Some ram will run at 4-4-4-12 at 800mhz (usually this is expensive stuff) But I think your ram will be something like 5-5-5-12
If you get too confused about this though you can just leave this option as auto hehe
Finally at the bottom is where you can change the voltages.
The default vcore is right at the bottom and is 1.35 to start with you can leave your vcore as normal as you might find your computer boots fine and is completely stable. However if it is not, the worst thing that will happen is that your computer won't post (turn on but nothing come up on screen)
Don't panic though, if this happens (which it probably will) just switch the power off to the computer completely and let it sit there a few seconds then turn it back on. The Gigabyte bios will reset itself and everything will be back to default values. IF it still doesn't post after pulling the power from it then you can clear the bios with the jumper on the motherboard, just check the manual to see where is it but from my experience you won't have to do this with your motherboard. They recover from failed overclocking attempts really well.
So if your computer isn't stable on normal vcore, you can try to bump it up a bit. You can see I've set mine to 1.45. I just picked this number out of the blue hehe but to be honest it's actually not going to increase the vcore much at all. That's because of a thing called vcore drooping. This is a problem where even if you give your vcore a new value there is sometimes up to .1 volts of "droop" that means the vcore will actually only be 1.35 anyway.
So in order to actually get your vcore up enough to make your cpu stable again, you need to set it to something usually above 1.45 but then again some boards don't suffer from as much vdroop as others so again it's something you'll have to experiment through trial and error with. I will warn you though, definitely don't put this value above 1.6 with your stock cooler hehe your cpu will get very hot
Ok then so once you've set everything to how you want it. You can save your bios settings and reboot and see if Windows works! Some things that can happen if it's not stable are basically, it will freeze on bootup, it might bluescreen, it might give some error message you've never seen before. In this case try going back into the bios and changing values accordingly. I would try upping the vcore a little more at first. For instance I had to put my vcore at 1.475 in order to get into Windows with my e6420 at 2.95Ghz
Once you are in Windows, start up coretemp and check your temps and start running Orthos
If your cpu starts getting up to 70c then it's probably not a good idea to run it for long and I think you should get a better CPU cooler. But under 70 I think is alright for a Core 2 Duo at full load.
If Orthos fails it is cause your cpu isn't stable at the speed it's at and you might need to de-clock it or up your vcore depending on what it's currently at.
And that's about it. I hope I covered everything. If you want to. Run 3Dmark06 before overclocking and write down your score then do it again after overclocking and see how much better it is