^+1 that's a good starting guide
By speed step, do you mean Turbo Boost? For 1800mhz RAM you must have 180 base clock I'm guessing. You can use speed step (EIST) at that speed, however, if you want to use Turbo Boost you're probably out of luck. I found the absolute max I could get was 175 base clock while using turbo boost. After that, the amount of voltage it needs get's stupid. On the other hand, disabling turbo I can run an even 4ghz (200x19).