PowerPC 970 vs 970FX

Discussion in 'Macintosh Computers' started by gekko513, Jun 25, 2004.

  1. gekko513 macrumors 603


    Oct 16, 2003
    I thought the 970FX was just a shrinked 970, but geek.com says the level 1 instruction cache has been upped from 32KB to 64KB.

    Why did they choose to increase just the instruction cache? Does anyone know how much this affects the performance?
  2. crazzyeddie macrumors 68030


    Dec 7, 2002
    Florida, USA
    Instruction cache is used to store the instructions used by the CPU. There will probably be no difference in speed (measurable anyway) by this increase. The Data L1 cache is the part of L1 cache that when increased can yield HUGE increases in speed due to its very very fast speed and location on the CPU. However, the L1 cache on most processors is not usually more than 32kb-64kb because it is very expensive. This is one of the main reasons that the Celeron processor (Intel) is so much slower (and cheaper) than even the Pentium 3-- it has very little L1 and/or L2 cache.
  3. gekko513 thread starter macrumors 603


    Oct 16, 2003
    If there's no measurable difference in speed, then why did they increase it when it's so expensive?
  4. mgargan1 macrumors 65816


    Feb 22, 2003
    Reston, VA
    geek.com made a mistake, the 970 and 970fx have the same amount of cache... the only difference is die size, the fact that the fx is built on a 300mm wafer, and it 90nm vs 130nm... plus the fx has strained silicon, SOI, and copper interconnects... the 970 doesn't have Strained silicon...
  5. Sun Baked macrumors G5

    Sun Baked

    May 19, 2002
    maybe geek.com should read the IBM documents again...

    But they can't since IBM locked the link that took you to quite a few of the documents.

  6. ddtlm macrumors 65816

    Aug 20, 2001
  7. zimv20 macrumors 601


    Jul 18, 2002
    mmmm... laptop-y....

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