check your mobo manual, but there should be an option like "advanced" or CPU or DDR or something similar. You'll find a whole bunch of memory timing settings like "CAS, RAS, something something something" 3 of the settings are obviously lower, and 1 is always higher. you have to check the specifications on your memory to see what the correct settings are, as it's also possible they follow normal spec and are detected as such and automatically configured properly.
looking on the internet searching for "change memory timings" or "configure memory timings" should help you find exactly what you're looking for, especially if you include in the search your mobo model #.