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  • Some Body - Friday, August 26, 2005 - link

    Can anyone explain why we have such a dramatic difference seen in this older article: http://www.anandtech.com/memory/showdoc.aspx?i=222...">Rewriting the rules
  • AtaStrumf - Sunday, August 14, 2005 - link

    I guess Dual core on S939 is the same as single core on S754, so gains/losses should be somewhat similar.
  • MemberSince97 - Sunday, August 14, 2005 - link

    Obviously samsung is going to drr2 because why ? My guess people want bigger dimms and current ddr 1x1024 dimms are not LL lol ,I am using crucial value 1gb dimms which are binned ballistics, and they work great. The thing is is they cant go any faster on current
    tech.
  • huges84 - Saturday, August 13, 2005 - link

    What software did you use for H.264 playback and encoding?

    What programs (on Windows) support H.264?

    BTW, Batman Begins was the best movie I have seen in a long time!
  • Creepy - Saturday, August 13, 2005 - link

    I want to know if similarly clocked processors with less cache would get more of a benefit from the greater bandwidth under the same conditions.
  • smn198 - Monday, August 15, 2005 - link

    Me too.
  • bupkus - Friday, August 12, 2005 - link

    I couldn't help but chuckle when reading about different plausable multi-tasking scenarios invented to test dual core memory bandwidth. It made me think of Steve Martin's role where he must pass a Viennese sobriety test in "Man With Two Brains," which required him to do a somersault, walk on one hand, then juggle and tap dance while singing "Catalona Magdelena Lupensteina Veleneina."
    I think since I have several older computers sitting around un/under used that I should put my KVM to use and multi-task the old school way. A little less pressure on the land-fill as well.
  • PrinceGaz - Saturday, August 13, 2005 - link

    I'm inclined to agree that a lot of the multitasking scenarios were quite contrived. I mean "Watching movies while you work" isn't a very practical proposition, not if you want to get any work done anyway :p
  • Aenslead - Friday, August 12, 2005 - link

    So... no upgrade from skt754 until M2 and DDR2, then.

    Great to see these things happen.
  • ElJefe - Friday, August 12, 2005 - link

    er well m2 ok, you can wait for that i guess. it will be a while before m2 comes out though. if you wait youll have to throw out your ram and gfx card, something to look forward to!

  • Araemo - Friday, August 12, 2005 - link

    I'm curious, does windows XP support NUMA?

    A quick google on the topic gives me conflicting info.

    People seem to think it does, if you manually turn on PAE(Which has its own performance overhead, right?), but MS's website says "NUMA is supported only on Windows Server 2003, Enterprise Edition and Windows Server 2003, Datacenter Edition."

    What I've read recently suggests that in the A64 X2 cpus, each core has one memory controller enabled, which suggests that NUMA could be usefull for performance reasons. However, what I read originally when the X2's were coming out was that one core simply had both its memory controllers disabled.. Does anyone know which of these two is correct?

    In any case, it sounds like memory latencies to different memory addresses will be different between the cores.

    Either one core will always have a higher latency, or each one will have low latency to some addresses and high latency to others.
  • Starglider - Friday, August 12, 2005 - link

    The Athlon64 die contains a dual-channel DDR memory controller, three hypertransport transcievers, one or two processor cores and a crossbar switch that links them all together. Adding an extra processor core to the X2 didn't duplicate any of the other parts, so no there aren't any disabled memory controllers on there. Both cores are connected to the memory controller through the switch, so they have equal access to both channels (which are interleaved anyway when both active). NUMA would not be relevant because the banks aren't independently addressable by the OS and deliver exactly the same bandwidth and latency to both cores anyway. NUMA is only useful if your system has more than one processor socket, i.e. is an Opteron system.
  • Araemo - Friday, August 19, 2005 - link

    Thanks for clearing that up for me, but the # of sockets really has nothing to do with it. It is the # of independant memory controllers that matters, and AMD could have placed multiple single-channel controllers on the die if they thought the performance would be improved, but if the memory controller is 'external' to the core(Accessable via HT instead of a more direct link.. not that HT isn't good.), then I guess it doesn't matter. I was thinking the memory controller was part of the same HT node as the CPU core, but the method you described makes more sense anyways. If you have the memory controller logically seperated from the core, it can serve DMA requests from the northbridge/southbridge without bothering the CPU at all, as DMA should be.
  • Diasper - Friday, August 12, 2005 - link

    It looks to me like future dual-core games will benefit from the extra bandwidth. The logic for that being using a high-efficient dual-core engine both cores should be demanding as much bandwidth as possible and so consequently, we might see something more akin to the multitasking with Doom3 performance numbers.

    Either way the numbers should be over the numbers we saw first time when testing dual-core with only a single-core game so say that's 5%+ im[provement at DDR500. Either way I think this information is pretty significant for those going with dual-core processors.

    Now where did my high sppeed low latency 1GB sticks go...

    Oh yeah and first.
  • Zebo - Friday, August 12, 2005 - link

    I don't know about that. Anand did'nt mention timings. I can only assume they are the same since he did'nt mention them at DDR400 and DDR480 respectivly... Which is faster? Who knows really... My feeling is if he let DDR400 at low latency it's capable of while DDR480 had high latency which it runs you would see neligible differences. Again not enough information...
  • Diasper - Friday, August 12, 2005 - link

    That's probably larger correct. I suspect they'll be running a similiar setup to before (http://www.anandtech.com/cpuchipsets/showdoc.aspx?...">http://www.anandtech.com/cpuchipsets/showdoc.aspx?... where they were running 2 x 512MB sticks that could do 2-2-2 timings all the way upto DDR500 or so.

    But yeah, can we get any clarification on that please - it's appalling that you didn't include your test system criteria although we can probably guess and trust it was done correctly.
  • Zebo - Friday, August 12, 2005 - link

    Yeah that VX stuff is most excellente.. The review I *really* want to see is how well DDR2 667 on M2 competes with say DDR 500 with it's new found low latency.. I have my money on "old tech":P
  • Diasper - Friday, August 12, 2005 - link

    Interestingly, looking at the results:

    For a 20% increase in memory speed we saw upto 10% increase in speed (approx) suggesting that X2 is bandwidth confined at least 10% when running full tilt so you'd be looking to be running at least DDR440 speeds or otherwise be risking lessened performance.

    Of course, given the uneveness of memory requests from both processors, I guess we could presume they would benefit with more memory speed although benefits would lessen above a certain speed (eg the guesstimate DDR440) as it is unlikely that you'll typically come across a scenario where both processors are demanding maximum memory bandwidth at the exact same moment.

    I guess that's speculation at best - but unless your an engineer that's about all you can do...
  • Spacecomber - Friday, August 12, 2005 - link

    I think we can assume that it is the same set up as with the first article, as the previous poster suggested.

    From the article:

    quote:

    The details of how to select these speeds and the hardware we used to do so can be found in our first article .


    Space
  • Diasper - Friday, August 12, 2005 - link

    [q}http://www.anandtech.com/cpuchipsets/showdoc.aspx?...">http://www.anandtech.com/cpuchipsets/showdoc.aspx?...


    Ah, well I probably shouldn't skip over stuff so quickly to get to the results - however why when in the previous test was the memory run at DDR500 now run here is only run at DDR480?

    That rather nullifies the comparative significance of the test as the same test wasn't run. :/
  • Anand Lal Shimpi - Friday, August 12, 2005 - link

    DDR480 is the fastest speed you can run on the Athlon 64 X2 4800+ on the DFI board using the new dividers. DDR500 is possible on the Athlon 64 X2 3800+.

    Take care,
    Anand
  • Diasper - Friday, August 12, 2005 - link

    Also, a further point might be to examine how running 4 x 512MB sticks at 2T might affect things - I guess we can say the bandiwidth loss of running it at 2T will affect performance significantly so compared to someone running DDR500 @1T with decent timings.
  • Diasper - Friday, August 12, 2005 - link

    Moreover, I guess AMD's move to DDR2 does begin to make sense as when both cores are fully taxed that bandwidth will be needed.

    DDR2 is set to get cheaper while timings are also tightening
    eg Corsair's new 512MB sticks that are rated at 3-2-2 675mhz stuff and have been o/c to around 709mhz or their 1GB sticks which are doing 3-3-3 at DDR533 (http://www.hothardware.com/viewarticle.cfm?page=4&...">http://www.hothardware.com/viewarticle.cfm?page=4&...

    In short it seems that DDR2 is getting much closer performancewise to DDR but offers guaranteed bandwidth which X2 can clearly benefit from. 1GB modules that do DDR500 are few and expensive whereas while that's still true of DDR2 now, DDR2 is still being developed where we will see future refinements providing lower latencies/higher speeds at an increasingly affordable price point - DDR is no longer being developed while it is feasible that DDR and especially premium sticks might get more expensive as the market slowly shrinks.

    In all, AMD have probably picked a rather opportune time to migrate to DDR2.

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