How to change from cas2 to CAs3

[CooCoo18]

i think my computer is automatically setting my cas3 ram to cas2... this may sound good but i have noticed the system crashing serveral times while running programs that require lots of memory (quake III)is there anyway i can fix this?? there is no option in my BIOS that gives me the option to change it to Cas2 so i really dont know how. I think i know this because i used the program CTPD and said ram was 2-2-3 which i think is cas2.

 

[TunaBoo]

If there is no bios option, it looks at the first stick and gets ram timings from it.