Processor Confusion

Discussion in 'PowerPC Macs' started by ppcg4mac, Mar 27, 2012.

  1. macrumors 6502

    ppcg4mac

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    #1
    i have a G4 (gigabit) with the original, dual450 processor, an eMac with a single 800 and another G4 that i was given for free (still gigabit) with a single 1GHz. All of them have 512MB of RAM installed. How come the dual 450 is WAY faster in general than all the others? in my mind the 1GHz one should rule, yet it is really laggy and slow.


    Sorry if this is a bad question.
     
  2. Moderator emeritus

    r.j.s

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    #2
    Because the 450 has two processors, rather than one.
     
  3. thread starter macrumors 6502

    ppcg4mac

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    #3
    thats what i thought, and then again 450x2=900 so they are about the same.
     
  4. Moderator emeritus

    r.j.s

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    #4
    It doesn't quite work like that ... the dual can do 2 things at once, rather than one thing twice as fast.
     
  5. macrumors 68020

    zen.state

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    #5
    The G4 800MHz in that eMac is a 7450 with only 256k L2 and no L3. The dual 7400 450MHz has 1MB L2 per CPU. Pro tower vs. underpowered consumer machine.

    The other single 1GHz is in a gigabit ethernet tower? It doesn't make sense that it would be slower as it would be a 7455 with 2MB L3 if it's a 1GHz in a G4 tower. It should be a bit faster in most ways and even faster in code with no dual CPU optimizations.

    Could be other factors but the eMac at least should be a good amount slower.
     
  6. macrumors 68020

    Jethryn Freyman

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    #6
    A single CPU can still multitask..
     
  7. Moderator emeritus

    r.j.s

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    #7
    Well, yes, through allocating different CPU cycles, but a dual-processor machine can actually do two tasks at once. One on each CPU, while still allocating the cycles like a single-proc machine would.
     
  8. thread starter macrumors 6502

    ppcg4mac

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    #8
    i got both gigabits for free, so its a good deal.

    The eMacs were 40 for 4 on CL and im preparing to sell them
     
  9. macrumors 68020

    Jethryn Freyman

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    #9
    Ah yes I guess you'd be right there, only trouble is when you come across something that's only single threaded, so when you're playing with such low clock speeds I'd probably go with the double-MHz single.
     
  10. adddictedtomac, Mar 27, 2012
    Last edited: Mar 31, 2012

    macrumors regular

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    #10
    Glad you mentioned that. My PowerMac G4 450MHz DP beats my MacMini G4 1.42GHz in many things. Here is a startup showdown, on Mac OS X 10.5; you will be impressed!

    http://youtu.be/x5Bz-gM9gMg
     
  11. macrumors newbie

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    #11
    Have you also considered the speed of the hard drive in these machines.
    i.e. Do they all have a 7200 rpm hard drive or a 5400 one?

    I think 512 MB is 'on the lowish side' for Mac OS X 10.4 and I wonder if a (virtual memory) swap disk is being created?

    That would really slow the machine down.
     
  12. thread starter macrumors 6502

    ppcg4mac

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    #12
    Both of the G4s use a Seagate barracuda 80GB 7200. the eMacs still have the original "Fireball 3" Maxtors, no idea on the rpm there.
     
  13. macrumors newbie

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    #13
    I think the Fireball 3 were 5400 rpm.

    I find the drive does slow down your machine on the cusp of the OS relying on its swap disk.

    Similarly I found that to be the problem with the Mac Mini if you don't give it lots of RAM, I've always been tempted to insert an SSD in one of these to see how well they would run! :)
     
  14. macrumors regular

    Joined:
    Mar 8, 2012
    #14
    Do not forget two things:

    1. The megahertz myth (related to CPU speed, frequency is not the only factor)

    2. In those chips, in order to increase frequency, IBM also increased pipeline stages.

    So, this means a 900 MHz chip is not necessarily twice as fast as a 450MHz chip if they doubled the pipeline stages.

    Just my opinion.
     

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