Memory question for the experts

Discussion in 'Computers' started by Christian Behrens, Dec 23, 2004.

  1. Christian Behrens

    Christian Behrens Supporting Actor

    Mar 2, 2000
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    SF Bay Area
    Real Name:
    Christian Behrens
    Can a memory module act both as registered and non-registered?

    I have a Samsung 512 MB SDRAM DIMM that works flawlessly in my Asus board, which the instructions say does not take registered RAM. But this module looks like a registered module, and the number says so, too:
    PC133R-333-542-B2, Samsung part number M390S6450BT1-C75.

    Other registered modules do not work, but this one does, when by itself.

    Strange? A coincidence?

  2. Chris

    Chris Lead Actor

    Jul 4, 1997
    Likes Received:
    While the board doesn't take (in as, does not support; the chipset provides no support for registered memory) it does not mean all registered memory will fail to function. Some registered memory will, by sheer chance, work in boards without functionality to support it. Registered memory is simply normal memory with an extra component.. these registers, which lie in between the control memory and the incoming data bus (CPU/board) simply help insure reliability and add about 1 extra clock time per cycle to hold memory which helps limit errors.. (errors occur all the time in the RAM world; your computer simply deals with them and adjusts, uncontrolled or continuous errors, like bad ram, etc. are a different deal; but cache misses, incorrectly buffered data.. etc. all the time) Ok, so that having been said, some boards will freak at registered modules because the timing is almost always off compared to what they expect for latency.. some boards will take it.. and some registered modules seem to "pass" as is.

    This doesn't make life easier for you to know what's what, but the easiest way to make sure this will never work right is to mix registered with unregistered memory.. you go all one or all the other; and if you're board doesn't by design support registered, your odds of making multiple sticks of registered work are very low.

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