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January 1st, 2010 17:00
Dual-channel Memory Options
I have an Inspiron 1440 (Best Buy model) with 3GB RAM (1x1GB+1x2GB). CPU-Z reports that my memory configuration is dual-channel. I was under the impression that in order to have dual-channel, both modules needed to be the same density (capacity). Is this correct or is CPU-Z correct?
I'm considering buying a matched pair of 2GB SODIMMS (PC2-6400) to give me a total of 4GB. Do you think this would give me much of a performance boost? The computer came with Windows 7 Home Premium 64-bit.
RAM is kind of expensive right now and since this is a budget laptop, I'm not sure if the performance gain would be worth the cost. I could save money by buying a single 2GB module and replacing the 1GB SODIMM with it. But then they wouldn't be a matched pair. As long as both modules are both PC2-6400 and have the same latencies (timings), then I should get dual-channel mode, right? Even though they would probably be different manufacturers?
Davet50
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January 1st, 2010 19:00
No having two modules of the same size has nothing to do with dual channel the individual sticks themselves are dual channel. Now in order to reap the full benefit of having dual channel is that all memory need to be the same. so in your case with the 3 gig you are not reaping the full benefit of running dual channel. what you need to do is look as the speed tab on CPU-z to find the speed that the memory is running at. My guess is that if your memory is spec'd at say 400mhz right now it is running less than that..
since your ram is fairly expensive i don't feel you will get much of a boost for what you need to spend.
raydabruce
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January 1st, 2010 20:00
It says it's running at 399.0 MHz., 6-6-6-18.
On the memory tab it says: Channels #: Dual; DC Mode: Symmetric; FSB:DRAM 1:2
So, I'm assuming it's saying "Channels#: Dual" only because the memory controller is capable of running dual-channel modules. Correct?
Davet50
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January 2nd, 2010 05:00
well actually it is reading the chip on the memory sticks themselves. There is a small chip on each memory stick which houses the SPD settings which in effect program the memory. It sets things like the timing levels and refresh rates and other things. This is what the actual memory controller which is part of the motherboard chipset reads. And yes you are correct in that the memory controller is set to run dual channel memory sticks.
kirkd
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January 2nd, 2010 18:00
The RAM modules are not inherently dual channel. The design of the system board controls how the memory is used. Newer computers allow dual channel operation with unequal sized modules. DDR, DDR2, DDR3 module are Double Data Rate modules, and this is different from dual channel. Dual Channel configurations have slightly better performance over Single Channel configuration.
With 3GB of RAM, the 1GB module operates in dual channel mode along with 1GB from the 2GB module. The third GB operated in single channel mode. If you upgrade to 4GB, overall RAM performance does increase, but you probably will not see any real difference in operation.