Dragon, I sympathize with you...I have the exact same prob.
I have a MSI KT7 Turbo-Raid w/ Duron 700
I was able to change my multiplier to x8 on my first try and boot up fine...after, when I tried to change to a higher multiplier, my system won't even POST...just getting power to fans and HDD. I can't seem to change the multiplier at all now and my system won't POST if I change the multiplier or the voltage.
The weird thing is that my friend and I bought the same MB/CPU combo from the same place at the smae time...he got the non-raid version of MB but the MOBO is exactly same otherwise. He is currently running at x8 and 111FSB very stable. I can't even seem to get my system to run stable at just the default multiplier and 105FSB...It seems weird that he has no probs yet I can't even seem to run stable @ 756Mhz
I have been desparately trying to get some answers from someone with no success....I will keep let you know if I find out anything...please do the same for me. You can find my thread below
http://forums.anandtech.com/messageview.cfm?catid=28&threadid=363704
Good luck!!! To both of us....