I got a P4 2.66Ghz 533FSB with 2x256MB 1066Mhz Samsung RIMMs.
The board is ASUS P4T533-C. The FSB is at 133 so 20X CPU multiplier gives 2.66Ghz CPU clock, while RIMM is running at 8X the FSB at 1066Mhz.
I got a chance to get 4x512MB 800Mhz ECC Infineon RIMMs for cheap and am willing take the hit in terms of RAM refresh rate from 32ns to 40ns. 1066RIMMS will be taken out altogether.
My question is: since 800Mhz RIMMs use FSB of 100Mhz, how will my processor respond to this? Will FSB fall to 100Mhz and the CPU will slow down from 133MhzX20 (2.66Ghz) to 100Mhzx20 (2Ghz)? Is a 2.66Ghz Northwood processor compatible with 800Mhz RIMMs any way?
No, your new memory should run @ 133 x 6 = 800MHz.
Since your CPU FSB runs @ 533MHz (effective) the 800MHz memory should be great.
I think it's a good plan and will really help your rig,