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Consufion over FSB speed and Ram

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January 30, 2010 11:32:10 PM

Hello everyone. According to Crucial.com my dual channel RAM slots are fitted with DR2-667 PC2-5300 Ram modules. My understanding is this would indicate a bus speed of 166MHZ: 166 * 4 (quad pumped for DDR2) * 8 bytes = 5300. According to CPUZ my FSB is 266MHZ and according to Intel the FSB is 1066MHZ. Why am I not seeing 166MHZ anywhere?

Help!
a c 128 } Memory
January 31, 2010 12:18:02 PM

Cpuid should list 667 ram speed at 333 unless you're overclocking. Cpu fsb varies with speedstep enabled in the bios; you can disable it on some boards. Overclocking and the speed could be anything; the board usually selects the proper ram speed according to the overclock and motherboard memory ratios.
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a b } Memory
January 31, 2010 12:47:57 PM

dmurray9133 said:
Hello everyone. According to Crucial.com my dual channel RAM slots are fitted with DR2-667 PC2-5300 Ram modules. My understanding is this would indicate a bus speed of 166MHZ: 166 * 4 (quad pumped for DDR2) * 8 bytes = 5300. According to CPUZ my FSB is 266MHZ and according to Intel the FSB is 1066MHZ. Why am I not seeing 166MHZ anywhere?

Help!

DDR2-667 RAM means the RAM is rated for an FSB frequency of 333 MHz - remember DDR2 transfers two chunks of data each bus cycle.

Your FSB frequency is 266 MHz. Only the processor bus is quad pumped. That means it transfers 4 chunks of data into and out of the CPU each FSB cycle. Your FSB clock is 1066 MHz. That's where the "1066" comes from.
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January 31, 2010 10:00:19 PM

I understand better now - but why then does CPUZ list FSB at 266MHZ if DDR2-667 is rated for 333MHZ? Thanks.
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