Max FSB greater than max RAM speed? (intel 965)

in intel mobile 965 chipsets, the max FSB is 800MHz,
and the max mem. speed is 667MHz.
does it mean that 800 MHz RAM will work at 667MHz?
is it worthless to install 800MHz RAM (instead of 667MHz) on intel 965 chipset?
another question: if there is two memory chips, one 800 MHz and the another 667MHz, does the second forces the first to run at 667 MHz?

 

Yes

Yes (If you're not into FSB overclocking)
Though both DDR2-667 and DDR-800 nearly cost the same.

Yes

 

If i install 667MHz RAM, (and the processor supports 800 MHz) does the FSB run at 800 MHz?
If the RAM is 667 MHz, what's the benefit from the 800MHz FSB?

 

Yes

Real-World: no real benefit. Theoretically, the benefit is bandwidth related. And the memory multipier will be 1.xx rather than 2, so overclocking will be a bit easier.

 

why does some notebook manufacturers sell notebooks with 965 chipset and 800 MHz RAM?
btw, is there real benefit from 800MHz memory (for example, on intel GM45 chipset)? what is the difference in the bandwidth?

 

I dunno why. It'll just downclock to 667MHz.

Check out this guide. You'll probably find info regarding DDR2-667 vs DDR2-800 bandwidth results. Performance difference is minimal though.