Dual-Channel RAM question

By iMoose
Apr 11, 2009
  1. Hey guys! Moose the meat popsicle here, and I have what may very well sound like a stupid question.


    So I have an Asus P4S800D-X mobo, and "building" my first system from the proverbial scratch. I've scoured the interwebs, yet cannot find a definite answer to this possible strategy.

    I have bitten the bullet, and bought some matched pairs of OCZ Platinum RAM off the ebay. I'm an extremely cheap bastard, so I will usually wait for months to get a deal. There's no way I could pay retail for OCZ, not that it's not worth it, I'm just too cheap.

    And my mobo has 4 slots. 2 blue, 2 black. I understand that I'm to put the 2 matched 512Mb(stop laughing!) sticks in the blue slots in order to achieve "dual-channel", but when I go to upgrade to some more RAM, does it have to also be 2x512Mb? So all 4 slots are "equal"?

    If that didn't make any sense, let me ask it this way.....

    Will my mobo recognize two additional sticks of paired RAM if they are larger? Like instead of 2x512, I get 2x1GB? Could a nearly double difference in RAM "size" confuse my mobo?

    Should I move the smaller guys to the black slots, letting the bigger guys nest in the blue slots? And out of curiosity, why would it make any difference.

    And let me also state that any opinions offered would be greatly appreciated, as I see there's other people in here with much bigger fish to fry. So....thank you to all!

    And here's a cool picture of a very happy lil' critter! For no real reason.

    Attached Files:

  2. captaincranky

    captaincranky TechSpot Addict Posts: 11,454   +1,759

    The channels should be balanced for correct dual channel operation; IE, 256 blue 512 black for each pair of sockets.

    The only thing that is true in all cases is the socket nearest the CPU must be populated or no bootie.

    Different boards react differently to unbalanced RAM. A board might successfully run in "dual channel interleaved mode" with 1GB in one channel and 1.5GB in the second channel. In this example only 2GB (total) would run in actual dual channel, the "upper" 512MB in channel two would run in single channel mode. It would be accessed only after the "lower" 2GBs were in use.

    The situations above are based on Intel's explanation of dual channel operation, with their chipsets in their boards. Different boards have different quirks. But, to a certain extent, you can even mix different speed DIMMs, and still have dual channel operation. But, the timing and the voltage must be the same for all the sticks you are using.

    I have mixed and matched different capacity and speed DIMMs and still had dual channel operation. As always, your results may vary.
  3. iMoose

    iMoose TS Rookie Topic Starter Posts: 57

    Thanks Captain!

    And before anybody says it....I DID READ THE GUIDE posted by Tedster(?).

    I'm just wanting to make sure before I buy any more dang RAM. I have read that my mobo is picky when it comes to RAM.

    Any other opinions?
  4. kimsland

    kimsland Ex-TechSpotter Posts: 14,524

    Just to make it real basic here (Because captaincranky's post was too technical :D)

    Put both 512Meg Ram cards in one color only (as captaincranky said, the ones closest to the CPU)

    If you buy more (exactly the same) ram ie 2 x 512Meg of ram
    Put those two in the other color

    Effectively having 4 x 512Meg of Ram ie 2Gig (approx ;))
    I wouldn't purchase 2 x 1 Gig of Ram just stick with the 512s
  5. iMoose

    iMoose TS Rookie Topic Starter Posts: 57

    Thank you Kim!

    But apparently the jokes on me! I just realized the auction I won was for TWO 256Mb = 512Mb.


    So now I guess I'll have to keep an eye out for another 512 kit, so I can at least have a GB of dang RAM. Thank the gods that I don't game.

    At least it was cheap.

    *edit: And they ARE pretty, as far as RAM goes.*
  6. captaincranky

    captaincranky TechSpot Addict Posts: 11,454   +1,759

    Here's one cautionary note. The best "mix and match" perormance you could hope for is with "generic" RAM. By that I mean DIMMs that conform to the basic spec for their type. For example, the basic spec for DDR2 is 1.85 volts. However, high performance modules might require up to 2.2 volts to run at their rated speed. Sooo, you couldn't mix "generic" RAM with the high performance type.

    Now, if you walked into Best Buy and bought a stick of Kingston "Value RAM", and a stick of PNY "Optima", these would be more likely to coexist happliy, because they're "generic" types.

    If you have a mobo that's known as "picky", your best chance of success comes with buying RAM that's been tested by the board's manufacturer as being compatible.

    As far as the "legend" of dual channel RAM kits, I'm pretty sure you can walk into a store and buy two single sticks of the same type, brand and capacity, and acheive the same results as if you bought a "dual channel kit". If would cost a couple dollars more, this being the only reason not to do it.

    I don't know if this is too technical but you could acheive true dual channel operation by running a 512MB module in blue (or the "0" socket) in channel "A" and 2, 256MB modules, one in each socket of channel "B". Here again, best chance of success comes with generic or same brand DIMMS
  7. Technochicken

    Technochicken TechSpot Paladin Posts: 729

    This doesn't have to do with the real question, but that picture is a tarsier, right?
  8. iMoose

    iMoose TS Rookie Topic Starter Posts: 57

    I just stumbled across it on the interwebz. Cute lil' bugger, isn't he(possibly she)?

    And it seems to just absolutely LUUURVE that branch.

    Or be yawning. Perhaps emitting a high-pitched shrill?

    Dang, now I gotta google tarsiers.

    *edit: Yup. Tarsier it is!*
  9. iMoose

    iMoose TS Rookie Topic Starter Posts: 57


    Well, finally managed to win two sets of identical RAM!

    Won a pair for only $9, then lost a pair because the price went to $20(!), then waited and found another pair for $7 SHIPPED! :wave:

    So for what people seem to be getting for a 512Mb of Kingston, I have 1GB of OCZ Platinum.

    I was so pleased I took a picture of my new babies!

    And here's a weird question I've never even heard anybody ask EVER.

    I think it'll be a good idea to change the battery on my mobo, she's been sitting awhile and they're only $4. So, what precautions should be taken while changing that? Take out the RAM? Unplug everything everywhere? Is it very risky? Am I just stooopid? :blush:

    Well, here they are!

    Attached Files:

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