AT News Update: DDR2 Memory Performance

by Kristopher Kubicki on 2/25/2004 6:06 AM EST
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  • zhuzhu - Wednesday, March 10, 2004 - link

    Can anybody explain the term "internal clock of Ram" and "external clock of Ram" for me please? Thank you!!!
    Is it the same as the internal clock of the CPU?

    And i still don't understand why DDR2-400 is lowered to 100mhz?

    help me please !!Thank you sooooooooo much!!
    Reply
  • Jeff7181 - Saturday, February 28, 2004 - link

    It seems to me that DDR2 will start out like RDRAM. Only the richest people who count every last point in Sandra will have it. The rest of us will make do with a 3% performance penalty and keep using DDR.

    I always like to see more work done per clock cycle, just seems more efficient to me. But if this is happening at the expense of RAM timing... it may not be worth much until we're up to DDR800 speeds. Cause I think if manufacturers REALLY wanted to work with current stuff and make it better, they could extend the current technology up to DDR600 and squeeze out some tight timings. However... somewhere along the line it was decided that DDR2 would be better. So... out with the old, in with the new as always... hopefully this isn't another RDRAM fiasco.
    Reply
  • jpwoodbu - Friday, February 27, 2004 - link

    The extra 56 pins or so are probably going to be used to get more power to the RAM. Since they're running at a lower voltage they won't be able to get as much wattage over the power lines without going over on amps. Reply
  • Odeen - Friday, February 27, 2004 - link

    "The same thing could be said when DDR memory came out over SDRAM. At first it was not much faster than normal SDRAM but in time it scales much higher than SDRAM."

    Actually, the slowest official DDR, 100mhz PC1600 was 50% faster in terms of bandwidth than the fastest official SDRAM, PC133, which had a 1.06gb/sec bandwidth.
    Reply
  • Odeen - Friday, February 27, 2004 - link

    Well, if it's quad-pumped, shouldn't it be QDR, not DDR? After all, DDR wasn't "SDR2".

    That said.. if that "prefetch" and the number of bits in it merely have something to do with the pumpedness, then the DDR2 moniker is misleading, and I should, by rights, call it, SDR3 :)
    Reply
  • Dasterdly - Thursday, February 26, 2004 - link

    It's quad pumped. Reply
  • Cygni - Wednesday, February 25, 2004 - link

    Wasnt DDR2 originally supposed to include "Virtual Channels" like the old VC-133 that never took off? I remember reading about that way back when DDR first arrived. Reply
  • ViRGE - Wednesday, February 25, 2004 - link

    One last question: how is this faster, but still using the same width bus. It's still a double-pumped solution, and it's still a 64bit bus, so how is the last 2x being transmitted? Reply
  • Abraxas - Wednesday, February 25, 2004 - link

    since the ram will be operating at a much lower speed does this mean that lowest timings will be easier to achieve with the new DDR2-400 ? that seems like it will be more cost effective. Reply
  • Pumpkinierre - Wednesday, February 25, 2004 - link

    oops sorry still working on SDR + subtraction error should be:'56 pins more than ordinary DDR' Reply
  • joeld - Wednesday, February 25, 2004 - link

    Good question -why the increase? just to lower the internal megahertz? Reply
  • Pumpkinierre - Wednesday, February 25, 2004 - link

    #13 If it is the same bus width, why the 240 pins? 62 pins more than the ordinary DDR. Reply
  • DerekWilson - Wednesday, February 25, 2004 - link

    #12

    all the improvements really are improvements to enhance scalability, not performance.

    Think of it like this: its the same bus width and speed a. You can't do better than moving the maximum ammount of data across the bus in either case.
    Reply
  • Nighteye2 - Wednesday, February 25, 2004 - link

    It may be nit-picking, but the article mentions 5 improvements, of which only the most influential one will be negated by the lower clock. But doesn't that leave 4 improvements to make DDR2-400 faster than DDR-400, if only marginally so?
    Reply
  • KristopherKubicki - Wednesday, February 25, 2004 - link

    GDDR2 and GDDR3 are fairly different.

    Kristopher
    Reply
  • skunkbuster - Wednesday, February 25, 2004 - link

    "Actually have been waiting for PCI Express for sometime. PCI does not provide enough bandwidth for all the PCI cards I have installed. PCI Express will be able to provide the bandwidth I need. "


    but unfortunately, you will not be able to use your pci cards in a pci express slot.

    Reply
  • ViRGE - Wednesday, February 25, 2004 - link

    The doubled prefetch is just for normal DDR2, right? I'm just thinking that we haven't heard anything about this for GDDR2, so it's unlikely this applies to it. Reply
  • jpwoodbu - Wednesday, February 25, 2004 - link

    Is DDR2 really not in mass production? According to ati's website, they're using it on the Radeon 9800 PRO with 256MB of RAM. Granted, I know that the XTs are using DDR1 but I would think that DDR2 would have to be in mass production to be for sale on any ATI video card. Reply
  • Icewind - Wednesday, February 25, 2004 - link

    Yep, yep, I knew that DDR2 just simply wasn't going to happen anytime soon. Awesome, i'll be able to use my Corsair 3700XMS in my Athlon 64 939 pin and save some bucks.

    The message is clear, DDR2 is poo!
    Reply
  • retrospooty - Wednesday, February 25, 2004 - link

    Yes, well in order to get it, you will need a new CPU, Video card, and RAM all at once. Reply
  • epiv - Wednesday, February 25, 2004 - link

    Actually have been waiting for PCI Express for sometime. PCI does not provide enough bandwidth for all the PCI cards I have installed. PCI Express will be able to provide the bandwidth I need. Reply
  • retrospooty - Wednesday, February 25, 2004 - link

    With the (at first) expensive DRR2 that, for the time being offers no performance improvement... And the Prescott that offers no performance improvement.. And the PCI express chipset that offers no performance improvement. I think Intel Sales are going to seriously lose way to AMD this year.

    Think about it... To go with the latest Intel i925x chipset, to be released soon, you have to buy...
    1. New i925x motherboard
    2. New Socket 775 Prescott CPU
    3. New PCI Express Video card
    4. DDR2 memory.

    All this will give you no performance advantage over the current offerings. Of course, I realize that later on, maybe next year the Prescott may hit >4ghz, DDR2 may hit 667 mhz, and PCIx will have newer PCIx chips, but for 2004, its not looking too good.

    I'm thinking Socket 939 A64 pretty heavily now.
    Reply
  • mikecel79 - Wednesday, February 25, 2004 - link

    "Does this seem like new technology just for the sake of new technology?"

    DDR1 is at the end of it's life. It's getting very difficult to make it any faster than it is now with good timings. DDR2 is in it's infancy and will scale to much higher speeds than DDR1 will.

    The same thing could be said when DDR memory came out over SDRAM. At first it was not much faster than normal SDRAM but in time it scales much higher than SDRAM.
    Reply
  • shiftomnimega - Wednesday, February 25, 2004 - link

    Does this seem like new technology just for the sake of new technology?

    I mean most people are saying, "Duh," but if there is no improvement over regular DDR right now then who cares about this and who is going to buy it?

    At least Athlon 64 had performance increases in 32-bit land.
    Reply
  • buleyb - Wednesday, February 25, 2004 - link

    I'm always happy to see new tech make it to the mainstream, but 240 pins? Man, laying traces for those DIMM slots must suck. This is the reason serial ram will come about soon enough. Reply

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