new to oc, need m/b help

I am going to switch to a Northwood soon from my current 1.8w and wanted to oc it. I was under the impression at first that going with a DDR m/b was the way to go, but I am seeing other posts still claiming that you can't beat the rdram. What I want to know is which is really better and why. Will the rdram m/b be faster and more stable than a DDR board or are they similar? Please give all advice you can. Thanks in advance. BTW, I was stuck between the SD7-533 or the th7-11.

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