yep cpu-z is the way to go...
when you do find the ram settings and there say 6-5-5-21 or anything higher than cas 5 then consider binning it in favor of 2-4 gigs of cas4 ram.. also its better to get 2x2 gigs or 2x1 gigs rather than 4x1 gigs as you can be assured you will be able to run in dual channel mode. reason being some cpus will only allow ram below a certain speed to be stacked on 4x1 single channels rather than 2x2 dual channels.
anyways what ever you find with cpu-z post here and we can then help you find the best ram for your board/cpu combo
next time you post, post the motherboard make and model and the ram make, mode and speed.