am2+ limited to 1 stick of 1066 ram per channel ?

Discussion in 'Processors and motherboards AMD' started by chaotic1, Jan 6, 2009.

  1. chaotic1

    chaotic1 Ancient Guru

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    i was reading the memory support list for my mobo and it said the following

    is this correct ? , i was hoping for 4 x 2gb in my next upgrade
     
  2. Psychlone

    Psychlone Ancient Guru

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    Could be a limitation of your motherboard, but I can tell you with 100% certainty, that AM2+ boards in general do not have this limitation. I have run all 4 banks of both my M3A32-MVP and M3A79-T populated with DDR2 1066 and didn't have any problems at all.
    So, it is clearly not an 'AMD AM2+ CPU limitation'...

    Psychlone
     
  3. chaotic1

    chaotic1 Ancient Guru

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    thx for the info , looks like a new mobo will be on it's way soon . i have just looked at other gigabyte mobo's and the 790gx says the same in the memory support list
     
    Last edited: Jan 7, 2009
  4. Antichrysler

    Antichrysler Member Guru

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    Please explain the 3rd line in the memory section here then.
    http://www.asus.com/products.aspx?l1=3&l2=149&l3=789&l4=0&model=2503&modelmenu=2
     

  5. Psychlone

    Psychlone Ancient Guru

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    I'm not about to correct information directly from the manufacturer - I'm going to tell you what I've done from experience. I *never* speak without having first hand experience - check any of my posts in the last 5 years...when something comes up that I don't have prior experience with, I leave it to people that have.

    So, in that, I can tell you that I've run 4 banks of DDR2 1066 RAM in both my M3A32-MVP and the M3A79-T Deluxe.

    I have read, however, that some people find it problematic to run DDR2 1066 in more than 2 banks, but I've yet to experience any ill effects.

    I don't run my 4 X 1GB DDR2 1066 sticks all the time since it's much harder to overclock with all 4 banks populated - I have 2 different sets of PC2 8500C5Df Dominator, the one I use most are the 2 X 2GB v1.1 sticks, the other is 4 X 1GB v1.3 sticks. (both being D9GMH - B63 ICs)

    From this CPUz validation very early in the overclocking stages of my first (of 8) Phenom CPUs, you can clearly see that I'm running 4 X 1GB sticks in the M3A32-MVP Deluxe (even though CPUz still shows them as PC2 6400, (which it still does due to 1066 not being fully JEDEC compliant) but if you do the math on 3:8, you'll find out that the divisor ratio is 2.66 - which is what 1066MHz RAM equates to, , *and* also you can see that they're running at 573.4MHz (1146.8MHz).
    http://valid.canardpc.com/show_oc.php?id=350811
    [​IMG]
    So don't tell me that it can't be done.
    Again, I only speak from experience...

    Psychlone
     
    Last edited: Jan 7, 2009
  6. Antichrysler

    Antichrysler Member Guru

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    So,your two top of the line(at the time)Asus boards can do what AMD says they can't.Lucky you.
    But two Asus boards hardly constitutes "AM2+ boards in general".
     
  7. Chris16v

    Chris16v Member

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    Im confused. I run 4 sticks of 1GB DDR2 1066 without issue.
     
  8. Knox

    Knox Ancient Guru

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    From the sounds of it, it's more bios related then anything.
    http://forums.amd.com/forum/messageview.cfm?catid=12&threadid=97916

    Do you have any proof that AM2+ CPU's can't run four 1066 dimms?
     
  9. SuaSponte

    SuaSponte New Member

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    I too can definitely confirm - also on the basis of actual first-hand, real-world experience - that you CAN populate both slots in each channel with DDR2-1066 RAM and configure all sticks to run at their rated 1066 speed by using the appropriate BIOS settings, and they will all work just fine (CPU-Z reports each stick running at ~533 Mhz in dual channel mode).

    I've used OCZ's Platinum DDR2-1066 and OCZ recommends 5-5-5-15-22-2T and 2.1v settings (not the mobo's 1.8v default vDIMM setting) in the BIOS (my OCZ Plat's are totally stable at 2.0v on my current mobo and they clock in at 533 MHz at that voltage with those timings).

    I believe that AMD offers this misleading disclaimer simply because most motherboards WILL automatically default to a lower speed when using 1066 unless you manually adjust the motherboard's BIOS settings as per the (RAM) manufacturers instructions - and also because some older motherboard BIOS's probably don't even offer those required adjustment options.

    This is another case of AMD's misleading "cover your butt" disclaimers meant to cut down on tech support calls from people who don't read the setup instructions that came with their 1066 RAM - it's like the other disclaimer that you also usually see right alongside this one, stating that 32-bit WinXP can't "recognize" 4GB of RAM, and suggesting that you install 3GB or less with 32-bit Windows XP! (32-bit WinXP see's all 4GB just fine, but it only "reports" what is left "unused" after all the background system processes and IGP shared memory requirements, etc, have grabbed their share).

    AMD apparently prefers to mislead occasionally (or simply tell a little white lie) rather than do even a minimal amount of actual explaining or clarifying. After reading those two disclaimers, that's my conclusion anyway, for what it's worth.

    The bottom line is that DDR2-1066 runs just fine in all the slots, if your motherboard supports it, and once you have the memory set up properly in the BIOS.
     
  10. Antichrysler

    Antichrysler Member Guru

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    So far I can see that Asus seems to have this worked out.Has anyone gotten 4x2gb 1066 running on them or any other make?
    The latest bios update(last week) for my board has just allowed me to be able to run 2gb sticks @1066.I only have 2 so can't check to see if 4 will run or crash like these 2gb's did before the update.
     

  11. Psychlone

    Psychlone Ancient Guru

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    I personally don't use anything less than an ASUS top-shelf board anymore.

    I really am sorry for your (perceived) luck Antichrysler. Maybe you can get ahold of a couple more sticks and give it a test on your Gigabyte board...that black print in the manual really means nothing to me - mine says that too, so maybe your board is capable of this as well.

    On my 'general AM2+ boards' comment, I do know of an MSI K9A2 board and an MSI DKA790GX board currently running 4 populated banks at DDR2 1066, the DFI LP DK 790FXB-M2RS, the ASRock K10N780SLIX3 and the Foxconn Destroyer 780A, both of which are nVidia chipsets, so it's not just AMD chipset boards, and it's not just ASUS boards that are capable - add to that that we're talking about 4 different Northbridges as well. (it's kind of surprising to me that Foxconn can pull this off, I've always considered them to be bottom of the barrel myself, but then again, I've only had one of their boards and hated it so I never went back to them, poor BIOS support IMO)

    I'm leaning towards SuaSponte's claim of AMD 'covering their butts' when they say that this type of configuration is unsupported. Even on the M3A32-MVP and the M3A79-T, you have to set the memory speed manually, along with the first 4 latencies, otherwise, sometimes you can't even boot - but it does this even with 1 stick in, so it's not always just a 4 stick issue.

    Most often, the BIOS will drop the divider down to DDR2 800 automatically when more than 2 sticks are inserted...if the BIOS has the ability to be manually reset to DDR2 1066, then it's easy, if the BIOS lacks this functionality, the only way to get them back up there would be to drop the CPU Multi, NB and HT and raise the FSB to increase the memory speed. This would probably be a motherboard limitation in itself considering the memory controller is different on the Phenom with it's ganged mode being 2 DIMMS on a single channel vs. the older X2 architecture that lacks this functionality altogether.

    In any case, it is being done. And perhaps it can be done on your board too...
    If/when you do get to testing this, please do post back so that others with your board can know it's possible.

    Psychlone
     
    Last edited: Jan 8, 2009
  12. SuaSponte

    SuaSponte New Member

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    AMD sure isn't doing the RAM and mobo makers any favors with their inaccurate disclaimers. They aren't doing us end-users any favors either. They're even shooting themselves in the foot with them.

    Given that the AMD Phenom has it's own IMC, the disclaimer sounds like it just might be credible, from a technical standpoint.

    In fact, however, it clearly seems to be merely a legacy motherboard/BIOS limitation only, and not an accurate reflection of the Phenom and its IMC capabilities and compatibilities.

    AMD has always been a rather schizophrenic company in this particular regard, though; on the engineering side they usually show genuine technical brilliance, but when it comes to software support, documentation and public relations their efforts are usually notably sub-par.

    Before buying my OCZ 1066 memory I visited the OCZ website. The OCZ forums are overflowing with questions about running 4GB or more of 1066 on the AM2/AM2+ platforms. I felt rather sorry for the OCZ staff after seeing such a huge deluge of questions (all generated by AMD's silly disclaimer) since the problem is obviously an issue of whether your motherboard and it's BIOS can handle DDR2-1066 settings, rather than any problem with the RAM itself.

    The ASUS web forum for my M3A78-T motherboard was equally saturated with inquiries on this issue. I almost didn't buy that particular motherboard after reading the AMD disclaimer that ASUS had posted in amongst the mobo specs.

    Because AMD is lazy and misleading, the mobo/RAM makers are taking it in the teeth, customer support wise, and many people are surely steering away from the AM2/AM2+ platform or away from DDR2-1066 RAM on those platforms simply because of the [unnecessary] doubts that the AMD disclaimer has created. It's just bad, incomplete, inaccurate info, and AMD is totally to blame for it.

    AMD really ought to just fire their entire Support and Public Relations staff and start over from scratch with those two departments. This sort of idiocy must just drive their poor engineering staff (not to mention AMD's stockholders) to tears.

    If you still have doubts, please check your RAM and motherboard manufacturer's websites before committing. Better safe than sorry, for sure.

    I found OCZ's forums to be a real goldmine of information on this issue, and much of what I learned there was equally applicable to just about any RAM/mobo maker's product. OCZ was more than happy to do what AMD was not: provide a wealth of solid, reliable information on this particular issue.

    Question: has anybody that's reading this tried running 6GB (1x1GB plus 1x2GB in each channel) in a 3GB + 3GB configuration? My mobo documentation says that I can run different sized sticks (at the same speed) installed in one channel in dual channel mode, and that it will default to using the smaller-sized module, along with an equal sized hunk of the larger module's capacity, in dual channel mode, with the remainder of the larger module's capacity configured as single channel. But can I use two identical sets of different-sized modules in both channels?
     
    Last edited: Jan 9, 2009
  13. Psychlone

    Psychlone Ancient Guru

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    Aside from version number difference, but yet both being D9 ICs, I can check for you later on and post the results tomorrow (I'm at work right now). I have 4 X 1GB and 2 X 2GB, all in D9 ICs, all with matching latencies, so this should answer your question.

    Give me until tomorrow...I'll pm you directly letting you know that I've updated this post.

    Psychlone
     
  14. SuaSponte

    SuaSponte New Member

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    Many thanks!

    I'm sure many start with 2x1GB and might later wish to add a 2x2GB kit. If half of that upgraded capacity is going to be forced to run in single channel mode, no matter what combination or pairing they are installed in, it would be nice to know in advance.
     
  15. chaotic1

    chaotic1 Ancient Guru

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    looking forward on seeing the results
     

  16. Psychlone

    Psychlone Ancient Guru

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    Sorry for the late reply Chaotic, I ended up being screwed into a double-back at my restaurant (yeah...the restaurant that I own - seems more like I bought myself a job rather than the way it's supposed to be!)
    Anyway, I'll check it out for you when I get home today and post the results ASAP.
    Sorry for keeping you waiting.

    Psychlone


    ***EDIT*** - Testing Done


    Yepper - it sure can.

    http://valid.canardpc.com/show_oc.php?id=480993
    [​IMG]

    [​IMG]

    I did drop my overclock to 3GHz in anticipation of it borking with my 3.51GHz standard with my 2 X 2GB sticks, along with leaving Bank Interleaving on [Auto], but changing Channel Interleaving from [Disabled] (since I don't normally have another channel in operation) to [Xor of Address Bits 20:16, 6] - and nothing else (meaning I left all my timings where they were, RAM set to 1066, UNganged)

    I should mention that I *still* had CnQ enabled as always...

    From the Everest Cache and Memory Benchmark, I lost a couple hundred MB/s on each of the areas, but not really much at all, and I'm pretty sure that I could tighten that up and get more throughput pretty easily - even with all 4 banks populated.

    So there you go Bro...the yellow slots have 1024 sticks in them, the black slots have 2048 sticks in them, for a channel total of 3GB x 3GB and a combined total of 6GB working just fine.

    Hope that helps you out!!

    Psychlone
     
    Last edited: Jan 10, 2009
  17. chaotic1

    chaotic1 Ancient Guru

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    thx for the results dude ;) most useful
     
  18. SuaSponte

    SuaSponte New Member

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    Yay!

    You have my deepest thanks for going to all the trouble to check that out for us, Psychlone!

    That's good news! My heart sings! ;-)
     
  19. chaotic1

    chaotic1 Ancient Guru

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    it works on my mobo , just installed 2 more gig of Corsair 2GB DDR2 XMS2 Dominator PC2-8500C5 . so i now have 4x1gb of 1066mhz ram installed on my gigabyte ma-770-ds3 , going to bench it now :)


    [​IMG]
     
    Last edited: Jan 12, 2009
  20. Psychlone

    Psychlone Ancient Guru

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    Sweet! Congratz!

    I'm glad it does indeed work on the Gigabyte GA-MA770-DS3.
    Now where's Antichrysler to test on his Gigabyte GA-MA790FX-DS5???

    I think it's important to get this kind of information out to the public so that they can be informed by people that have actual experience with it rather than having to be confused by what the motherboard's manual says...

    Any other AMD AM2/AM2+ motherboard owners that have the ability to test this should post in here - this could be a very useful resource to many, many people!!

    Good job Bro.

    Psychlone
     

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