i'm stuck at the same place you are. i'm running 450 FSB and can't get my memory to 1800 for that 1:2 ratio. i've upped vMEM and vMCH both to levels i wasn't entirely comfortable with and loosened my memory's timings all the way up to 9-9-9-28. still no love.
unfortunately, i have to run my memory underclocked at DDR1500 until/if i get this straightened out. i'm surprised that my DDR1600 memory can't overclock that little bit more. i may have overlooked something though. i haven't given up yet.
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