A Tip On Socket 939

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In the next few days, we will see socket 939 systems being benchmarked, most of the time against socket 754 systems.

There’s something one ought to keep in mind when looking at the numbers. There are two key differences between a Newcastle socket 939 CPU and a Clawhammer socket 754, and they pull in opposite performance directions.

  • The Newcastle socket 939 has dual-channel memory. That helps it against the single-channel Clawhammer.
  • The Newcastle socket 939 has only 512K cache. That hurts it against the 1Mb Clawhammer (3400+ and 3200+).

    The Newcastle 3500+ will run at the same CPU speed as the 3400+ Clawhammer. Which one will do better in a particular test depends on what is more important for the app or game being tested; cache or more memory bandwidth.

    It should not dismay or shock you to see the 3400+ Clawhammer win sometimes. That just means cache is more important than more memory bandwidth for that particular activity.

    Nor should AMD be blamed or denounced for rating the socket 939 Newcastle slightly higher than the Clawhammer despite the Clawhammer winning sometimes. Overall, and particularly for games, the Newcastle probably will edge the Clawhammer.

    It should also be kept in mind that neither a doubling of cache nor dual-channel memory perform wonders even under the best of circumstances. It’s pretty rare either contributes 10% to performance, and often enough, the increase is less than 5%, occasionally hardly any at all.

    Again, it depends on what is being tested. If the app or game doesn’t even use the memory bandwidth available with single-channel memory, doubling it isn’t going to do very much good.

    If an app or game makes little use of cache, putting in more isn’t going to help, either.

    Both situations occur pretty often.

    The Real Reason To Prefer Socket 939

    The reason why you’d prefer socket 939 in the long-run is much the same reason why DDR2 and PCI Express will be a better bet in the long-run. It’s not what you get today, but what you get tomorrow.

    In all three cases, new advances are going to occur here, not in socket 754, DDR, or AGP.

    The key term here is “in the long-run.” That doesn’t mean the same as “buy it now.” It does mean “let this affect when you buy.”

    Again, one size doesn’t fit all. If you know full well that you’re going to replace anything you buy soon within a year or so, this argument doesn’t much apply.

    Once the smoke clears from Computex, there will be those who will say, “Why should I buy a socket 939 processor for $400 when I can get a socket 754 for $150-175 with a cheaper mobo to boot that does only 2% less overclocked than the expensive system?

    Well, that’s a good argument for not buying a socket 939, but that doesn’t necessarily make it a good argument for buying a socket 754.

    The problem is, those who are in that position usually aren’t going to be doing any upgrading again anytime soon, and they may be better off going with a cheap socket A today, and waiting twelve-eighteen months to upgrade to whatever dual-core wonder (or at least upgradable to such) is available then.

    Email Ed

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