spensor

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May 28, 2009
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i have 6GB of Corsair XMS3 1600MHz and i am trying to get them to run at 1600MHz but for some reason i cant so maybe you guys can help. I have a Asus P6T Deluxe V2 MB and in the bios i set the Ai Overclock tuner to XMP mode and the bios says the DRAM freq was DDR3-1600MHz yet in CPU-Z it says the DRAM Freq is 801.8MHz. Does anyone know why its not running at 1600MHz, or even 1333MHz. I hope you guys can help.

Also i would like to thank you all for you help so far, you all have helped me out a lot with the new computer i put together. Thanks
 

spensor

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May 28, 2009
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Really, well then thank you very much!! So why do you need to multiply the freq CPUz shows by 2?
 

flyin15sec

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DDR stands for double data rate, a simple way of describing how memory talks to the CPU from those who engineer things, not me. Basically if you have DDR2 memory, then you mulitply the DDR memory by 2. However for DDR3, the multiplier is still 2.

So for 1600mhz DDR3, the DDR rate is 800mhz.
 
Yep. It's a matter of effective vs real clock rate. DDR3-1600 has an actual IO clock of only 800MHz, but it has an effective rate of 1600 because it does 2 transfers per clock cycle.