My findings is that RAM speed doesn't help alone - in fact running your CPU off 1:1 actually makes your system slower
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I ran future mark 06 once at 3.0ghz FSB 333, 1:1 ram, RAM = 667 --- got 12026 marks
I rebooted and O/Ced the RAM and when I rebooted I Ran future mark 06 at 3.0ghz FSB 333, 1:2 ram, RAM = 800 --- got 11977 marks
So I guess the answer is keep your RAM at 1:1 unless it benefits you to overclock your processor.
I need better cooling to be able to overclock my processor so I guess I'll just stay at 3.0 with a 1:1 RAM divider, and underclock my 6GB (2x1 & 2x2) of PC6400 RAM
Just run futuremark 06 at both levels and come back and share the results.