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What exactly determines memory speed? (several questions about CPU-z o

This is the output I get from CPU-Z in my new laptop (it's a packard bell easynote butterfly touch):

And now I have several questions:
First of all, I wonder why the DRAM frequency being used (400MHz) is not listed in the Timings table of the SPD tab. In fact, the timing used (Memory tab) are 5-5-5-15, but the closest in the SPD tab is 5-5-5-18. Does this mean that something is wrong, or at least sub-optimal, in my computer?
Second, the FSB of the CPU is 800MHz. Does it mean that the memory can work at 800MHz maximum? Can't I use the 533MHz (7-7-7-20) mode in any way? Unfortunately, I don't have any screen capture of the BIOS settings, but there is very little to change there: no overclocking options and very, very few information about memory.
Finally, I want to put another DIMM of RAM to make it 4Gb. Will it automatically make it work in double channel mode? There is something else I should be aware of?
In a quick internet search I found that the most readily available 2Gb DDR3 SO-DIMMs are 1333MHz. Is there any chance that because of some clocking incompatibilities my system would end running at 667MHz instead of 800?

Thanks in advance for your answers and help
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  1. Best answer
    Your FSB to Dram ratio determines the RAM speed. Since you have a ration of 1:2 at FSB of 200, multiply by 2 to get 400mhz. This ram could run at 533mhz, it would require the FSB to change to 266mhz, or the FSB to DRAM ratio change to 1:2.65. If you want to , or can, you can overclock the FSB to 266 to get the memory (and everything else) to run faster. I dont know if it can OC that high or not.

    If you add another chip it will run dual channel automatically, no need to do anything.

    New ram will run to what the FSB dram ratio computes out to, if it is on automatic, it may have setup problems.

    Also dont worry about the timings, they dont really mean that much anymore. The SPD timings are what is programmed into the RAM to tell the computer how fast to run. THey dont always use the SPD timings though, so dont worry.
  2. Best answer selected by porio.
  3. This topic has been closed by Maziar
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