You have to enter your BIOS - by pressing delete on boot.
My Gigabyte MOBO should had an Intelligent Tweaker - as the first menu option. Go inside there - and look at the screen. In the submenus - there are alot of options set to auto as a default.
If you are comfortable tinkering - go look inside a couple of those menus and select manual vs auto - and see what's in there. ( stick with the DRAM menus )
I had enough curiosity to figure out what to adjust when I built my first PC - but not enough to walk you through it. But if you make sure you only adjust timing by entering the values that come with your RAM - and voltage as directed by your RAM modules - you can probably figure it out.
There is no standard BIOS menu - my understanding is the menus vary based on boards and brands.
Found this @
Motherboards.org