DDCSpeed, you set you CAS level in your BIOS. You will need to read your motherboard manual to see what the specific setting is called, but it might be something called "Memory Latency." It should have a default setting of 3. Really advanced motherboards, like some of the Abits, will allow you to adjust all sorts of memory timings besides this, but those don't usually show the same performance increases.
Low-end motherboards don't allow you to adjust the latency at all, so you might be out of luck.