Wow thank you for your replies.
Now the Biostar TForce965PT board takes ddr2 800 ram.
With that would I have to oc the ram aswell?
Cause you do talk about OCing the 667mhz ram.
Thanks again for your help!
It should have a 1:1 memory ratio, that's what you typically want to use when overclocking.
Very roughly, OCing a C2D works like this:
CPU speed = multiplier * FSB
RAM speed = 2 * ratio * FSB
The default FSB is 266MHz, and the E6300 has a multiplier of 7, so 7 * 266 = 1862MHz is where we get its speed from. At a 1:1 ratio, the RAM frequency is 2 * 1:1 * 266 = 533MHz ("PC2-4200").
Raising your FSB to 340 MHz would get you:
CPU = 7 * 340 = 2380MHz
RAM = 2 * 1:1 * 340 = 680MHz <- just a wee bit over spec
If you're worried about this
Notice: Only DDR2-800 memory supporting JEDEC approved 1.8V operation with timings of 5-5-5 or 6-6-6 is supported on Intel Desktop Boards based on Intel 965 Express Chipsets.
I think it applies only to 800MHz RAM or higher. Basically, if your RAM is incapable of running settings like that at 1.8V, you won't be able to boot. Most 800MHz RAM comes with a default SPD setting that accommodates this so you can at least boot and get into the BIOS to change the voltages and timings to their proper values. If you buy 667MHz RAM, this shouldn't be an issue.
Now, one thing we haven't asked is what you've got now (can any of it be re-used - obviously not the RAM, but case, PSU, HD, etc), what your budget is, and what you plan to use your computer for. Depending on all that, we might be able to better ascertain what the best choices would be.