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Question About Memory Utilization With FSB

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January 15, 2010 5:42:46 AM

I am using an older (2006) laptop, running Windows 7 Pro 64 Bit, a Mobile AMD Sempron 3400+ 1.8GHz processor and 4GB of matching Kingston DDR2 667MHz RAM. I know that according to the standards set by JEDEC that DDR2 667MHz is clocked at 333MHz (though the true reading says it's around 301MHz according to CPU-Z). I am running in dual channel (obviously) but was wondering since I am running Dual Channel and even though CPU-Z says I'm running at 333MHz, am I truly utilizing the whole 667MHz? The FSB on my computer is rated at 1600MHz (checked the specs at the manufacturer website and at AMD) so if I am, I know the FSB is fast enough to run it, and won't be bottle-necked. Also, if I'm utilizing the whole 667MHz, why doesn't CPU-Z or any other hardware identifiers show the actual combined channels as 667MHz per stick of RAM?
a c 128 } Memory
January 15, 2010 12:04:07 PM

It does. 333 is multiplied x2 to get 667. Under "spd" it lists the possible speeds and recommended timings for each type of ram the board can use. Cpuid isn't perfect; my ram is listed at 398.6 when it should read 400.
January 18, 2010 12:20:50 AM

o1die said:
It does. 333 is multiplied x2 to get 667. Under "spd" it lists the possible speeds and recommended timings for each type of ram the board can use. Cpuid isn't perfect; my ram is listed at 398.6 when it should read 400.



Under "SPD", which is what I was I was referring to, it says the max bandwidth is 333MHz, With 5, 5, 5, 15, 20 @1.8v as my timings located under JEDEC #3 and at the Max Bandwidth section. Under "Memory" it says I'm running at 301.4MHz, FSB: DRAM CPU/6, 5, 5, 5, 15, 21, and a command rate of 2T. I should be running at 333 or better, because the computer is slightly overclocked by 0.46%. Though I used another program (CBID) and though it's not made for 64 bit, it said my MAX was 266MHz and was running roughly at 6, 6, 6, 18, 24. That doesn't even make any sense because with those timings I should be running somewhere around 400MHz according to the memory charts I read in the memory forum. So I think CBID is wrong. Anyways, what I'm trying to figure out now is if my FSB is supposed to be 1600MHz, why is my RAM not maxed out at or near 333MHz (x2) and why does my computer not seem as it's running Dual Channel at 667MHz? I'm running roughly minimum services, and my processes are barely using any processor speed, so I know it's not that, and I'm using 2 Gigs for processes and services on average out of 4, according to the Task Manager.
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a b } Memory
January 18, 2010 3:25:39 AM

Silent_Observer said:
----- DRAM CPU/6, 5, 5, 5, 15, 21, -----


I believe it is because you have it set at CPU/6 so 1600/6 = 266 MHZ if you want it at 333 you need to set the DRAM divider at CPU/5 for 320MHZ since that is the closest to 333 you can get with a 1600 MHZ
January 18, 2010 3:43:04 AM

As far as I know, I have the latest updates for my BIOS, and it's read only (I am using a laptop, so limited to changes in the BIOS) . So how do I change the Divider if I have no way of changing it from the BIOS? Are there any programs I can use that will work with 64 bit?
a c 128 } Memory
January 18, 2010 11:24:53 AM

Probably not. Most laptops aren't designed for overclocking. You were lucky to get stability with the overclock you have now. The bios may be preventing the system from crashing by reducing the ram speed. If it's stable, I would leave it alone, or run at the default settings.
January 18, 2010 6:31:28 PM

I don't think it's the BIOS. The overclocking I have done is a "soft" clock, using Crystal CPUID, and has to be manually re-initialized after every reboot. Only thing that changes from that is the voltage from 1.150V to it's MAX 1.200V giving me the 0.46% overclock, and bumping me from 1800MHz to 1808MHz on the processor. It is before and after reboot still at CPU/6. Even after I change the voltage back to 1.150V. Thanks for the input though.
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