weirdest PB problem I've ever heard of -- wrong CPU on right logic board?

Discussion in 'Macintosh Computers' started by California, Sep 15, 2005.

  1. macrumors 68040


    Aug 21, 2004
    Okay. I just bought a pristine used 1ghz Tibook. Cosmetically pristine. Superdrive had failed, okay, I knew that beforehand.

    Then I pop in more ram to the the thing and the CPU speed on the "about this mac" under 10.3.9 reads 667mhz??!!!!!!!!!!!!!!

    I know the logic board was replaced in the first year of warranty on this machine so I make some bitchy calls to the certified apple repair place and inquire as to how they could have put on a 667 board on a 1ghz machine. Call Apple who tells me that they did indeed ship out a new logic board to this company at athat time. 1ghz board.

    Then I notice that it IS actually a 1ghz board because it is stamped so on the memory bar atop the board. The serial number is also a 1ghz, though there is no serial number onscreen under the "about this mac" spec window.

    WHAT is going on? Could a superdrive failure be affecting the logic board's CPU. AND THEN, the original Fujistu hd fails, forcing me to boot up from an external hd via firewire. What, what, what is going on?

    Can a failing logic board register at lesser CPU factor than it is built for?

    Does the failed superdrive/and now hard drive have anything to do with the lesser CPU rate?

    I'm stumped. My first impulse is to get it to an Apple tech and have a new cd drive and hd put in to see if this is the remedy, but the fact the thing is working at a depressed CPU speed is very very very weird.

    Any thoughts, anyone?
  2. macrumors 68020


    Jun 29, 2004
    Holy moly! That's weird... my guess is it's a software error, that it's reading something incorrectly. Bring it to apple. They'll work it out.
  3. macrumors 6502

    Apr 29, 2004
    Auckland, New Zealand
    Interesting... The superdrive on my 1ghz Ti also failed.. As well as the HD not long ago.. Meh, my fault for not getting apple care. :(
  4. thread starter macrumors 68040


    Aug 21, 2004
    I'm hoping it's something like that. Hope I can get a new superdrive to me quick enough that I can replace it and see what's up. One thing the Apple guy said to me about this is -- "remember, the superdrive is attached to the logic board..."
  5. thread starter macrumors 68040


    Aug 21, 2004
    The most trusted Apple tech guy I know said that it is a dying processor.

    This computer was basically DOA -- dead superdrive, dead hd, dying logic board. I wonder if it isn't the heat factor on Tibooks, especially 1ghz that seems to do them in so fast.
  6. macrumors Penryn


    Dec 27, 2002
    Location Location
    So what are you going to do? Can you do anything?
  7. macrumors 65816


    Feb 10, 2003
    Buckeye Country, O-H
    those powerbook's don't have jumpers for controlling the clock speed do they? I know that some of the older G4's have jumpers, and so did the G3's, but i am not sure if the Laptops do or not.

    i would think that someone either stuck in a slower processor, or your jumpers are set for a slower speed.
  8. macrumors newbie

    Jun 10, 2004
    I had a 1GHz Tibook, and while it never did this, I vaguely recall a lengthy discussion on the Apple boards regarding this issue.

    If memory serves, incorrect processor speed reporting was a relatively common problem with this model powerbook. I believe this was discovered because the machines would still turn in 1GHz G4 benchmark scores even though they indicated that they were running at only 667MHz when queried in various ways through software/the terminal/etc... (667MHz being the "Reduced" processor setting, disabling the L3 Cache.) I think the fix was to reset the PMU or something along those lines. Of course, given the other issues you describe, it's certainly possible that something is actually failing.

    Is there a chance it merely "thinks" it's operating at 667MHz, or is it really running that slow?
  9. thread starter macrumors 68040


    Aug 21, 2004
    I will let you know Monday night, after I take it into the Apple tech guy. How do you reset PMU on a Titanium?
  10. macrumors newbie

    Jun 10, 2004
    I did more research to double-check; it appears that resetting the PMU resolves the issue of incorrect system clock speed reporting. You can do it yourself, here's the Apple Support page with pictures and instructions:

    I found a thread on this issue in the Macworld forums; Google "missing megahertz titanium" or go here:

    Maybe it's not really dying and is just confused. :)
    Hope this helps.
  11. thread starter macrumors 68040


    Aug 21, 2004
    Thanks RisingPhoenix; something's up because it'll go to 1ghz after PMU reset, but next start up, back to 667ghz. We'll see what's happening.
  12. macrumors member

    Sep 13, 2005
    Rural Alaska
    Are you still operating without an internal hard drive? I wonder if this has something to do with your problem. Consider yourself lucky. I can't get my tiBook to boot from an external HD at all.
  13. thread starter macrumors 68040


    Aug 21, 2004
    No I managed to get the internal drive to work by copying the panther loaded external drive in disc utility. But, having had bad luck with those internal Fujistu OEM apple drives, I know this baby is on her last legs. Much happier when I luck out with Hitachi Apple OEM drives. As a matter of fact, Apple should TELL us on the outside of the box what type of internal drive comes with it because I trust any kind of Hitachi IBM travelstar drive over Fujistu.

    FYI, northernleitz, another Tibook i had stopped working when the motherboard battery died. Check that out; it works great now. (400mhz with warrantied CPU overclock to 550mhz)
  14. macrumors 6502a


    Jul 7, 2004
    I remember reading some comments at Apparently a parameter which is able to read the clock speed in OS X is faulty and does not read the correct frequency. Perhaps your computer is reading this error and reporting it back to you. Dispite that fact, your PB should be running at 1 GHz still.

    Here is the article
  15. thread starter macrumors 68040


    Aug 21, 2004
    Thanks TDM21. Okay, now it makes sense. The macosxhints thread claims the problem is that the processor itself SLOWS DOWN when it is not being taxed, for heat reasons. AND it runs slower than you want it to whenever you aren't using it enough. This should have been spelled out for all PB users, because it looks like it is a problem on ALbooks too. Basically my Tibook decides when it wants to be used at a higher processing speed without my permission.

    I'm gonna "tax" it and see if the CPU speed increases. Still, interested in what the Apple tech has to say.
  16. macrumors newbie

    Jun 10, 2004
    Hmm... I would try to get a sense of how it performs in Xbench or a similar performance benchmark utility, anything that can give you a repeatable test that you can reference to see if it's really switching it's CPU speed or if it's just reporting it incorrectly. You may also then reference your scores to those of other 1GHz G4 machines, if they are dramatically lower that might be an indication that your processor isn't running at full speed.

    Some background:

    Aluminum Powerbooks were the first to feature "Automatic" processor and memory bus speed slewing. In earlier models this is called "Processor and Bus Slewing," in the latest models this is referred to as "DFS," or "Dynamic Frequency Switching." The "Automatic" setting in Energy Saver enables this feature, while the "Highest" and "Reduced" settings lock the machine into maximum performance or maximum power saving modes, respectively.

    My 1GHz Titanium Powerbook only allowed me to set the processor speed to "Highest" or "Reduced" and did not offer an "Automatic" mode. The "Reduced" setting on the Titanium would run the CPU at 667MHz and disable the L3 Cache (the 133MHz system bus speed was not adjustable on this model). The Titanium does not dynamically alter it's CPU speed. It appears to lack this ability on a hardware level.

    See 1GHz Titanium Developer's Notes here:
    (click on "Overview," then "System Software," then "Power-Saving Features")

    The early Aluminum machines dynamically switch their clock speed and bus speed when left on "Automatic," while the very newest "DFS" equipped Aluminum Powerbooks have done away with bus slewing entirely and simply halve their CPU speed under light loads. (I gather this was a move to make the barely speed-bumped 1.67GHz machines feel "zippier" (technical term) :) than their 1.5GHz predecessors, but it appears to negatively effect battery life).

    For quick reference links look here:
    15" 1.25GHz Aluminum PB rev A:
    (click on "Overview," then "System Software," then "Power Management")

    15" 1.67 GHz Aluminum PB rev C:
    (same as above)

    Hope this helps :)
  17. thread starter macrumors 68040


    Aug 21, 2004

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