Will DDR2 ram improve performance of new PB?

Discussion in 'Macintosh Computers' started by lssmit02, Oct 19, 2005.

  1. lssmit02 macrumors 6502

    Mar 25, 2004
    According to the tech specs, the new 15 and 17 have "512MB PC2-4200 DDR2 SDRAM (running at 333MHz)." Does this mean that the processor is now able to take advantage of DDR ram? Does the reference to "running at 333 mhz" mean that the data transfer rate of the front side bus has basically been doubled (167 x 2=334)?
  2. tekmoe macrumors 68000

    Feb 12, 2005
    i think it was changed to improve battery life...

    somebody correct me if i am wrong.
  3. bousozoku Moderator emeritus

    Jun 25, 2002
    Gone but not forgotten.
    The G4 itself will never be directly connected to the RAM. The system controller may be improved but it's still a bit of a two lane road coming from a 10 lane freeway. The actual speed is 166 and 2/3 so, you can see why they label it 333.

    I see no reason why switching RAM specifications would help, other than to use whatever RAM is in favour. It's all about giving the system controller better throughput to get and put data from/to that RAM.
  4. VogonPoet Guest

  5. jer2eydevil88 macrumors regular


    Feb 6, 2004
  6. Sun Baked macrumors G5

    Sun Baked

    May 19, 2002
    Probably not, the DDR memory really wasn't a staggering improvement over SDR due to the current FSB limitation.
  7. 50thVert macrumors regular

    Jun 20, 2005
    St. Louis, MO
    Exactly right. The bottleneck is the FSB to the CPU, not the ram throughput. It will help battery life out because it runs on 1.5-1.6 volts instead of 2.6-2.8. DDR2 also has higher latencies than DDR1, so its possible in some cases you might see a slight drop in performance, as DDR2 at the same speeds as DDR1 is less than stellar.
  8. Demon Hunter macrumors 68020

    Mar 30, 2004
    The G4 can't even use the full bandwith of DDR, much less DDR2.

    They changed the specification for supply reasons; DDR SO-DIMMs remain more expensive.

    I will be surprised if there is anything but a marginal performance gain. Maybe even a performance decrease because DDR2 has higher latency.

    Is there any upside to this? Sigh.
  9. 50thVert macrumors regular

    Jun 20, 2005
    St. Louis, MO
    At the higher latencys and same mhz, we will most likely see a performance decrease.

    The ONLY advantages i can see is a slight improvement on power consumption, and higher margins for Apple because DDR2 SO-DIMMS are cheaper than their DDR counterparts.

  10. cc bcc macrumors 6502

    Jul 3, 2001
    Well, the fsb can be saturated, and there would still be plenty of bandwidth left for the graphics card, firewire/usb/harddisk/ethernet to talk direct to memory.

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