memory - RAM and CPU compared to mobo clock

08
2014-07
  • AnhVu

    I have a general question concerning RAM and CPU speeds compared to a motherboard speed. Motherboards have e.g. 100-133MHz clock. CPUs have some frequency multipliers and memories I suppose have some as well. And here's my question. What CPUs and RAMs are doing while waiting for motherboard to tick? Is a motherboard frequency the frequency RAM and CPU are communication with each other? Thanks

    • Answers
  • Frank Thomas

    The System bus connects the CPU to the RAM, and operates at the same speeds the RAM does. This is why your CPU, Motherboard, and RAM all match in capacity (speed). Do not confuse this with clock speed however.

    You CPU and Motherboard should both indicate the speeds of ram they will support. buy ram at one of these supported speeds (even better, consult your motherboard RAM compatibility list), and you will have no troubles.

    See here for a list of common DDR3 speeds: https://en.wikipedia.org/wiki/DDR3_SDRAM#JEDEC_standard_modules

    Also, since you seem interested in clock ticks, remember, the first D in DDR is Double, because DDR performs operations on both the rising and falling edge of the modified tick.

  • Aboba

    They measure different things, like in a car you have RPM for an engine and your tires have a different RPM because there are gears in between. CPU cycles are used to perform math, ram cycles are used to input and retrieve data and motherboard cycles move data around.

    This is an oversimplified example, there are other things happening as well.


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    memory - CPU/RAM 'swapping'
  • fluteflute

    There are two machines in my household:

    1. A Dell Dimension 9200 running Ubuntu 10.10, with 4GB (4x1GB) of RAM and a Intel Core 2 E6600 CPU.
    2. A Dell Dimension 5150 running Windows XP, with 1GB (2x256MB, two free slots) of RAM and what I think is a Pentium D 820.

    (I think it is fairly obvious that machine #1 has the most 'power'.)

    Due to the uses of these two machines I would like to effectively swap their power, or compromise somewhere in the middle of the two (perhaps 2GB of RAM each).

    Due to the operating systems, programs and data on the two machines, simply swapping them, and starting from scratch (e.g. reinstalling, transferring data) from each is out of the question. What are my options to beef up the power of machine #2? I am not sure what compatibility issues I could encounter?

    I eagerly await the advice of the Super User...

    Update: the Dimension 5150 apparently has either a 945G or 945GZ chipset (according to Intel's utility) and according to the Dell website the Dimension 5150 has a PCI-E slot, from which I conclude machine #2 has a 945G chipset that could support the E6600 CPU.


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  • AndrejaKo

    Well, your question has more to do with motherboards than anything else. I don't know what Dell uses in its systems, but the swap may be possible. Here's information for Pentium D 820 and here's for Core 2 Duo E6600. From what I can see, they boths use DDR2 RAM, so there won't be any damage on the modules themselves if you do try to swap. You may have problems with memory frequency, but I suspect that E6600 would use faster RAM which should be able to downclock to the one used with 820.

    Those 3 GiB of RAM could come in basically 2 ways: First is 3*1 GiB of RAM. You'd them just take one stick from first machine and put it in the other machine. Second option would be a combination of 2+1 GiB. You'd have to identify the 1 GiB module and move it from one machine to the other machine.

    It could also happen that you have 4 GiB of RAM in 2+2 modules, but that E6600's mothermoard can detect only 3. I think that it is unlikely, but it's not impossible.

    You could also move processor from Dimension 9200 to Dimension 5150, but E6600 uses higher FSB and it there is a high chance that Dimension 5150's motherboard doesn't supoort it. I don't think that trying out E6600 would be dangeorus.