Try something

1. Turn on your bench rig with 45nm cpu. Set some frequency in bios and go to windows. 5GHz will be ok
2. Do all tweaks for 1m (priority etc) and run it few times. Notice your times.
3. Turn off your pc, take one ram stick and run pc with single channel.
4. Repeat 2nd point.
5. Increase your fsb, lets say 3mhz up and try one more time with single channel

You will be shocked, belive me
Is this the same for lower clocks (like 4Ghz) or only when you go beyond 550Mhz FSB?