You need to unlink the RAM from the FSB to stop it from changing, but a 1:1 ratio is usually best anyway. I have never used that RAM or mobo, but you may be able to get the RAM over 900MHz with just a slight voltage bump. Be sure to get the maximum stable CPU OC before trying to OC the RAM. It is usually better to up the speed than to tighten the timings with RAM. To raise the speed, you will probably need to unlink the RAM from the FSB but I am not sure how to do this on your mobo. I usually keep mine unlocked and just manually set everything.