How do i change the memory clock?

Jun 7, 2018
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I have 8gb (2x4) 1333MHz ddr3 but when i open CPU-Z it says that its running at 669.9 MHz.
How do i fix this?
My motherboard is a Gigabyte GA-M68MT-S2 (rev 1.3) and i'm running an AMD Phenom ii x4 945.