I have a gigabyte S3 and a Pentium D 820 , anyway i was wondering wat the "memory multiplier" option in the BIOS does

Memory Frequency = Memory Multiplier x FSB

For DDR, 1:1 Ratio is equivalent to 2x Memory Multiplier.

so what should i put put the memory multiplier to if im running DDR2 667 and FSB of 243mhz

What option do you have?
You shouldn't have problem running 2x, but 3x will overclock your memory a bit, and you might have to change the timing, or a bump in Vdimm might be able to do the job.

thanks for the help

You're welcome.
So what settings you got it at? 2x or 3x?

I have another question, is there anything wrong with running the memory at a 3:4 ratio

Nope, nothing wrong there, but you might lose potential performance.

Nothing at all. If im correct the 1:1 ratio lets the memory and bus run in sync and causes less overhead.

Ok this is why I am confused. you said 1:1 is the equivalent of 2x with DDR... but what does that mean.

What would the proccessor bus and procassor multiplier be? what speed would 667 DDR2 run at if the setting was 3x what would it be for 2x?