Yeah... It is recommended to loosen up your ram timing first before raising your fsb or OC. This is because you dont want your OC to be restricted by your ram or something like that.

So loosen up your ram and then start OC till you satisfy then only try to tighten up your ram timing. But bear in mind ram timing in Intel OC isnt that important compare to AMD rig as its wont affect much in performance.

You can get those nvidia chipset mobo where there is an option that you can 'unlink' your fsb and ram frequency.