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2800XP V's 2500XP

Discussion in 'AMD Thunderbird' started by SM, Aug 24, 2003.

  1. SM

    SM Guest

    Is it worth spending the extra £60 for the higher speed processor( both
    Barton Cores)
    I will be OC on a new DFI Lanparty NFII Ultra,

    is the 2500 more flexible?

    Any help & Advice wiil be greatly appreciated

    SM
     
    SM, Aug 24, 2003
    #1
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  2. SM

    J.Clarke Guest

    Not quite. Would you pay extra for a tire that was guaranteed to take
    full inflation pressure vs one that is guaranteed only to take 10 psi
    less than full inflation pressure? Or would you save a buck and pray
    that the cheap tire was merely mismarked rather than being actually
    unable to take the pressure?

    The situations are not analogous for a number of reasons, one of the
    major ones being that the worst that a failed processor does is become
    an annoyance while a failed tire can kill you and your family, and
    another being that tires that won't take full pressure are generally
    destroyed rather than being sold as seconds. If you want to use tires,
    then a better analogy would be a tire rated for 100 MPH being used at
    150 MPH.

    While all Bartons may be the same design and made in the same facility,
    that does not mean that all will run at the same clock speed. And the
    fact that you haven't personally encountered one that doesn't is not
    relevant to the general statement. Personally I've never met a
    sub-Saharan African with AIDS but that doesn't mean that they don't
    exist in large numbers.
     
    J.Clarke, Aug 24, 2003
    #2
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  3. SM

    J.Clarke Guest

    Actually, the question is whether (a) you need to run at the higher
    speed and (b) the (small) risk that the processor will either fail or
    perform erratically at the higher speed is acceptable to you. If you're
    designing bridges or monitoring life support systems then taking the
    risk is probably not a good idea. If you're playing SIMS then it's
    probably acceptable. That's a decision you have to make.

    Unlike Wes, I don't believe in overclocking everything in sight. There
    are times when it is appropriate and others when it is not.
     
    J.Clarke, Aug 24, 2003
    #3
  4. SM

    Wes Newell Guest

    Of course not. The answer is in your question. They are both Barton cores.
    IOW's, they are the same cpu, just with different defaults.
    Would you pay 50% more for a tire that was inflated to the max compared to
    the same tire that was inflated to the minimum tire pressure, when
    inflating it to the max would be the same as the first? Basically, that is
    your question.
     
    Wes Newell, Aug 24, 2003
    #4
  5. SM

    SM Guest

    OT
    go to tire tread NG????

    So tell me if I'm wrong
    1.You would buy the 2500
    2.your tire pressure is low
    3.why pay over-inflated??? prices for basically the same core

    Thanks

    SM
     
    SM, Aug 24, 2003
    #5
  6. I got the 2500+ Barton and overclocked it a little. I changed the FSB from
    166.6 to 200MHz and left the multiplier where it was at 11.0. I increased
    the core voltage to 1.7v. It is only a couple of degrees centigrade hotter
    at 2.2GHz than it was at 1.83GHz. I now have a 3200+ for $88US instead of
    close to $500.

    http://tinyurl.com/ku2b

    BTW, if your mobo won't handle 200MHz, you can just increase the multiplier
    from 11 to 12.5 to get the 2800+.

    There are quite a few threads on which Barton to choose in the
    overclocking.amd newsgroup.


    Too_Much_Coffee ®
     
    Too_Much_Coffee ®, Aug 24, 2003
    #6
  7. Mine is @ 12.5X215... get the 2500xp...
     
    John Theriault, Aug 24, 2003
    #7
  8. Post a CPU-Z or WCPUID image somewhere so we can see it.
     
    Too_Much_Coffee ®, Aug 24, 2003
    #8
  9. SM

    J.Clarke Guest

    Wrong. 2800XP is not the "same model" as 2500XP.
    And some rated at lower clock speeds won't run any faster than the rated
    clock speed.
    No, Wes, I'm not getting carried away. Anyone who has had any real
    engineering experience knows that designing a system so that a component
    is running out of spec is eventually going to bite you in the ass. And
    that is exactly what you are doing any time you overclock.

    You have some good advice for people, but your continued insistence that
    every processor in the world is going to work the same way that the few
    that you have personally encountered work is doing no service to
    anybody.

    When you have a thousand of those all running the same way reliably,
    with no rejects, then maybe I'll be impressed.
     
    J.Clarke, Aug 25, 2003
    #9
  10. SM

    J.Clarke Guest

    I see. So you just willy-nilly assume that every processor of a given
    design is going to perform exactly the same way as every other processor
    of that design. I have mixed emotions about my wishes for you in this
    regard--on the one hand I hope you continue to get away with this, on
    the other hand it will serve you right if the time you get audited is
    the time that the arithmetic functions on your overclocked processor are
    off just enough to get you nailed with a half a million dollar fine.

    There is something called a "manufacturing tolerance" with which you
    might wish to familiarize yourself.
     
    J.Clarke, Aug 25, 2003
    #10
  11. SM

    Wes Newell Guest

    The tires were the same. That means same brand and model. Only one was
    completely aired up. Note "same tire" above. Your response makes no
    sense.
    That's true, some rated at slower clock speeds will actually run faster
    than some rated at higher clock speeds. Proven fact.
    I think you're getting a little carried away John.:)
     
    Wes Newell, Aug 25, 2003
    #11
  12. SM

    Wes Newell Guest

    That's correct.
    Probably. I haven't driven my car in a few weeks.:)
    Exactly.
     
    Wes Newell, Aug 25, 2003
    #12
  13. His response makes a lot of sense. No two tires are the same. The same
    applies to CPUs. There is no guarantee that you'll get the 2500 to run @
    2800 speeds. I'm not sure if AMD does the same testing which Intel used to
    do. Intel would take processors to see if they passed a set number of
    tests. If the processor fails, they tested the same processor with lower
    settings ... and so on. Now if you know that AMD ran only one set of tests
    and marked the processor speeds randomly, you would be correct. Does anyone
    know how the testing is done?
     
    The TweakOholic, Aug 25, 2003
    #13
  14. SM

    foamy Guest

    While the tire analogy might have not been absolutely flawless, the
    point was clear and I think iy's a tad anal to critique it under a micrscope.

    Perhaps 2 motors, virtually with the same potential, one with a governor
    on, the other not ?

    Jim
     
    foamy, Aug 25, 2003
    #14
  15. SM

    Wes Newell Guest

    While this may hold true in bridge building, it has no impact when it
    comes to these cpu's. There are all built to the same specs. They may not
    all be tested the same, and one may clock higher than another, regardless
    of the model number. A 3200+ is just as likely to fail as a 2500+ clocked
    to the same speed, assuming it was thoroughly tested at that speed by
    whiever clocks it. The IC industry has been doding the same thing for at
    least 20 years. They build a part and then test to speed the order is for.
    There's nothing thrown in to make one part slower than the other, They all
    come from the same design. Now if you get a 2500+ that won't clock to a
    3200+ speed, then that's another story.
    I'm not sure what you think a few is, but I've probably worked with at
    least a couple of hundred. I can't recall one that wouldn't clock up to or
    close to the top speed of that core.
    Should have read this first. Nope, not that many.
     
    Wes Newell, Aug 25, 2003
    #15
  16. SM

    Wes Newell Guest

    Come on now, I never said that. In fact, I said just the opposite. Some
    will clock higher than others.
    I'm retired.:)
    But as I've stated before. I don't overclock critical operations machines.
    I designed and built memory controllers from ttl. I'm a litlle familiar
    with tolerances.:)
     
    Wes Newell, Aug 25, 2003
    #16
  17. SM

    J.Clarke Guest

    It holds true in _every_ kind of engineering.
    They are built to the same drawings, with a tolerance range. Some come
    closer to the middle of the range, some are on the edges. The ones on
    the edges of the range will not perform as well as the ones that are in
    the middle of the range.
    If they are all identical then why are they sold with different speed
    ratings?
    Do you have a definitive test cycle that will guarantee that any chip
    will perform identically to one with a higher rating from the
    manufacturer under _all_ circumstances? If so, please be kind enough to
    publish it, and publish the evidence on which you base the contention
    that your test procedure is adequate.
    No, they build a part and then test to determine which speed bin to put
    it in. In some cases, when they have more orders for a low-speed part
    than they have parts binned at that speed from a given run they'll
    downgrade part of a lot. But it doesn't always happen and all parts are
    not downgraded.
    They all come from the same design, but they don't all come from the
    same identical dopant composition--there are tolerances there. And they
    don't all come from the same identical dopant penetration, there are
    tolerances there too. And they don't all have the identical crystal
    structure--there are tolerances there. And they don't all have the same
    identical feature dimensions--there are tolerances there as well.

    Now it may be that AMD has their process tuned to the point that all
    parts produced will pass the tests for the highest speed, or it may not.
    But unless you work for AMD you have no way of knowing with certainty
    that that is the case.
    How do you determine that a given processor will clock to 3200+ speed?
    Modern processors have an immense number of states--take the
    transistor count and raise 2 to that power and you'll have an
    approximation--if you aren't privy to the design you're not going to be
    able to figure out which ones represent"worst case" and you aren't going
    to live long enough to test all states of a single processor, so how do
    you know that your tests are adequate?
    And on the basis of "a couple of hundred" you'll generalize to all the
    millions that are produced, under all operating conditions and you'll
    build mission-critical hardware with those out of spec processors?
    You'll trust lives to those processors? You'll trust billions of
    dollars to those processors?
    Another question. Are those processors all running reliably at "the top
    speed of that core" at the maximum rated temperature for the particular
    chip? The ones that are labelled with a particular speed are guaranteed
    to run at that temperature.
     
    J.Clarke, Aug 25, 2003
    #17
  18. SM

    SM Guest

    Thanks everyone for their help, 2500 barton on its way to me as we speak.

    SM
     
    SM, Aug 25, 2003
    #18
  19. SM

    Wes Newell Guest

    Now that's one's real simple. Supply and demand. When their customers are
    odering 1700+'s, they default them to 1700+'s, and test them for that
    speed. When they order 2600+'s, ditto. Otherwise, you wouldn't see any
    more cpu's from amd under 2600+'s in the XP line. Amd's actual cost is the
    same for the 1700+ as it is for the 2600+. It's all about supply and
    demand. Always has been, and always will be. As far the Barton, same thing
    holds true. Their cost for a 2500+ is the same as for a 3200+. Our cost
    however is considerably more.
    There are many test programs that are available. Me, I just get it to post
    at it's highest speed, run memtest, then clock it down a little to be on
    the safe side. I don't thnik you'll find what you are looking for
    anywhere, including at amd. If it were available, I don't think you'd have
    seen the recalls that have been put out by Intel for their cpu's.
    Then there are a lot of downgraded 1700+'s out there.:)
    Just look at the numbers. How many Tbred B cores have you seen reporting
    to run well over 2200MHz. Now how many have you heard people complain that
    they can't get over 2000MHz out of one. I haven't heard of a one. The
    proof is in the numbers.
    This is the way I do it. I get it stable as high as possible, then back it
    down at least 5%.
    There are no garauntees that running at the rated speeds won't cause
    unforeseen problems either. It's all the same.
    No John, You're trying to put words in my mouth that I didn't say. When in
    fact, I've stated just the opposite for critical applications.
    Now you know I never stated this.
    Anyone that would run a cpu at it's top rated temp is an idiot, just
    asking for trouble. You know that as well as I. As for the garauntee. Just
    try it. You'll be sending a lot of cpu's back. They will fail prematurely.
    You'll have to take my personal garauntee on that. And of course, the
    widely known fact that heat kills in the electronic component.
     
    Wes Newell, Aug 25, 2003
    #19
  20. SM

    Ben Pope Guest

    Well... not quite, but I'd expect it to be pretty much the situation in this
    case. Depends what proportion of Barton cores fail the 3200+ test, I doubt
    it's that many after they've been producing 3200+ for a little while.
    Does AMD have a definitive test cycle? Didn't think so.

    However, when running a prime95 test my 2500+ running at 3200+ speeds it
    does seem to consistently fail on one of the calculations. I haven't tried
    it at 2500+ speeds yet.

    Ben
     
    Ben Pope, Aug 26, 2003
    #20
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