Why is my CL7 RAM running at CL9 timings, and how do I fix this?

Question

As you can see in the following screenshot, I have CL7 RAM. (Part number)

However, CPU-Z reports that it is actually running at CL9 timings:

So, what is going on here, and how do I fix it?

Other specs:

CPU: AMD Phenom II x4 955
Motherboard: Gigabyte GA-MA790XT-UD4P

If anything else is needed to draw a conclusion, please let me know.