Well, the memory (HyperX) is tested to run at 800MHz but the SPD's are programmed to run at 667MHz so as to meet the JEDEC standard. You can find the same info in the Kingston website. You can set the frequency manually in your BIOS to 800MHz. For lesser overclocked RAM or a value RAM please visit the following webpage - Memory for Asus ASUS P5N-D Motherboard
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Good luck with the upgrade!!