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IS IT TRUE FSB has to be in the same clock frequency w RAM?

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January 14, 2006 1:34:04 AM

Hi all,
I am very confused about memory clock and the FSB of CPU. I read on some articles that FSB of the CPU has to be operating in the same clock with memory, that is synchronous.

For example P4 3.0 GHz , 800MHz FSB will have FSB:memory ratio 1:1 if it is working together with DDR2 400.

If I am using DDR2 667 then the FSB and memory ratio will not be working in the same clock frequency (asynchronous) and it will not give optimum performance.

Is that true for those case?
Thank you for your help.

regards.
a b } Memory
a b à CPUs
January 18, 2006 8:56:06 AM

DDR400 has the same clock rate as DDR2-400 and performs better.

Yes, both the 800 bus and DDR400 are based on 200MHz clock cycles, these run synchronously together.

But these days the performance difference of running asynchronous memory is not that noticeable.
January 18, 2006 7:46:41 PM

Quote:
DDR400 has the same clock rate as DDR2-400 and performs better.

Yes, both the 800 bus and DDR400 are based on 200MHz clock cycles, these run synchronously together.

But these days the performance difference of running asynchronous memory is not that noticeable.


Maybe for newer pc's you don't notice a difference. On my current machine, I ran Sandra tests before, during, and after putting up my fsb. Then i ran a tests just to see if 1:1 ratio works or not. With my ram being 1:1 with my fsb I run averagely about 9% better.
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January 18, 2006 8:16:25 PM

Well for best performance its best to do so.

With this memory you can overclock your 3ghz cpu to 5002,5Mhz without the memory being a bottleneck in your system.

Also if your memory runs lower than the normal speed you can lower the timings (in the BIOS, disable SPD, and try lower settings)
a b } Memory
a b à CPUs
January 19, 2006 6:39:16 AM

9% in Sandra's memory benchmark simply means your system is 9% faster in...memory benchmarks. I don't see the fun in those.

But you can see where assynchronously faster memory is actually performing very well in P4 processors if you care to look at SysOpt's memory reviews.
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