Wolf,

For your 4ghz setup, what is your FSB speed? To run 1:1, set your RAM speed to half of that. If you need to increase the speed of your RAM to get to a 1:1 divider, loosen your timings to compensate so that you remain stable. Once you've established stability at 1:1, you can then work to tighten timings, testing for stability as needed.

For my 4.05ghz run with my OCZ PC-6400 SLI 2x2 gig set, my FSB was set to 1800, RAM to 900mhz, and timings to 5-5-5-15-2T (other timings on auto.) vDIMM was set to 2.2v. Remember that proper settings for RAM at any frequency depends greatly on what RAM you have. If you have PC-8500 RAM, for example, you'll likely be able to run 900mhz with tighter timings. Also be sure not to exceed the maximum warranted voltage for your RAM, as DIMMS will fry due to overvolting much more easily than any other component in your rig.

With a QX9650, you have a great deal of flexibility in setting your FSB. Ultimately, you'll want to set your RAM so that your RAM's bandwidth is as high as possible with latencies as low as possible, while your proc remains at 4ghz. At times, lowering your RAM and FSB speed, while increasing your processor's multiplier (so that 4ghz is maintained) will result in more bandwidth and lower latency than with a higher set FSB. This is due to the ability to set tighter timings (and a 1T command rate) at lower speeds, and due to NB strap differences. Passing a certain FSB threshold may cause the NB to switch to a different strap which can have a drastic effect on bandwidth, despite your RAM and FSB running at higher speeds. If you can achieve 4ghz with your multi set to x9 or x10, test both and see which combination of multi, FSB, and RAM will result in highest bandwidth. Unfortunately I haven't tested the strap tendencies of this board, and it may very well differ between boards and BIOSes. Ultimately, the best way to find the best settings is by testing different combinations... overclocking is always a game of trial and error.