Why does my RAM say 400mhz when it should say 800mhz?

I have a PNY 2gb pc2-6400-800mhz RAM module. I opened CPU-Z and went to the memory section and it told me my DRAM frequency was at 400mhz. Because it is a 6400-800mhz I thought it would run at 800mhz. DDR ram runs at 400mhz why is my high grade DDR2 running at low speeds? It only says that it can go backwords to 533mhz, 667mhz, and max 800mhz. any help?
 

andrern2000

Distinguished
Jul 28, 2010
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DDR is short of Double Data Rate (DDR).

The speed you saw in CPU-Z is the speed for each rate. So the actual rate is double that 400x2=800 Mhz. Your memory is working normally.

So the 667 Mhz memory will be displayed as 333 in CPU-Z. 1066 as 533, and so forth.
 
Yes, it can be a little confusing. There is a big difference between memory frequency and memory clock. The memory frequency will match the FSB frequency. For DDR2, each bus cycle generates 2 memory clocks.

Everyone seems to use and define these terms a little differently.
 

edgeria

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Feb 20, 2012
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Thank you.. I Finally took a day off of work to overclock and I couldn't remember what ram I had. So I looked it up on Newegg and saw 1600 but then I remember I saw 800 in Cpu-z. and then I really was like huh.. Thank again.