Is the MacBook heat just simply related to Core Duo?

Discussion in 'Mac Pro' started by mac000, Jul 14, 2006.

  1. mac000 macrumors 6502a

    Sep 6, 2005
    I have noticed my MacBook getting pretty warm (hot) if u want to say just from using it for the internet.

    Is the heat just simply related to the Core Duo chip? And it being so powerful for the G4 (comparing it to the iBook G4 heat).

    I'm just wondering if this is similar across all laptops on the market with CORE DUO chips? holla ;)
  2. Mackilroy macrumors 68040


    Jun 29, 2006
  3. DeathToPCs macrumors newbie

    Jun 25, 2006
  4. river0 macrumors newbie

    Jul 17, 2006
    Is 75-85 too hot a range?

    My two-week old black MacBook runs 75 to 85 with two 1GB memory boards and runs 60-70 with two 256K memory boards.

    Two questions.

    1. Why would the temp range differ so much with diffferent memory boards?

    2. Is 75-85 too hot a range? It certainly is too hot to touch, and if the temp hits 90, Apple can tout this model as a hotplate. "Do a little surfing and then fry up an egg."
  5. kraftzwerg macrumors regular

    Jul 8, 2005
    With 512 MB memory, the harddisk is probably used a lot more than with 2GB of memory. I think the harddisk actually generates quite a bit of heat (telling from my external hard drive which gets pretty hot).
  6. andrewheard macrumors regular

    May 16, 2005
    Ontario, Canada
    But his got hotter with more RAM.
  7. QCassidy352 macrumors G3


    Mar 20, 2003
    Bay Area
    seems too hot to me. My macbook rarely even touches 70, let alone 75, let alone 85! :eek: I do only have 1 GB RAM, but my temp idles around 58-60 C and gets up to 66-69 C under load. The only time I've hit 85 is when something went screwy, the processors went up to 100%, and I had to do a hard shutdown... :rolleyes:
  8. tbrinkma macrumors 68000

    Apr 24, 2006
    With less RAM, the hard drive is used for swap more often, causing the processor to idle more often, causing less heat.

    RAM speeds are measured in nanoseconds, HDD seek speeds in milliseconds. That's a factor of 1,000 difference.

    A basic comparison:
    The CPU runs at approx. 2 GHz (2,000 MHz, or one cycle every 1/2,000,000th of a second)
    The RAM is accessed at approx. 600 MHz (1/3 the speed of the CPU, or about 1 'cycle' every 1/600,000th of a second)
    A random HDD seek takes about 5 milliseconds on a fast drive (about 1 'cycle' every 1/5,000th of a second)

    If the CPU can get stuff from cache, it has the instructions/data the very next cycle.
    If the CPU has to fetch from RAM, it essentially has to wait at least 3 cycles for the instructions/data to go from RAM to the cache.
    If the CPU has to fetch from the HDD (swap space or data on the drive), it has to wait at least 400 cycles for the instructions/data to get into RAM, where it can be fetched into the cache. That's 400 cycles that the CPU is idling.

    It's a bit more complex than that, really, because you're running more than one piece of software at a time, so the OS can keep the CPU from idling uselessly for large chunks of time, but with swap being used heavily, the CPU still sits idle for relatively large chunks of time.
  9. SC68Cal macrumors 68000

    Feb 23, 2006
    I learned something new today. Good post tbrinkma
  10. joebells macrumors 6502

    Oct 24, 2005
    Yeah the heat is primarily attributed to the core duo chip compared to the g4 chip. But apple still should have designed the notebook to be able to operate at full capacity without reaching 100 degrees. If that meant making it a quarter inch thicker to fit a bigger heatsink and fans or whatever then they should have done that. Instead they went for asthetics over functionality. It is nice how they made the ram slots and hard drive easily accesible.
  11. Mackilroy macrumors 68040


    Jun 29, 2006
    Joebells: the MacBook CAN reach maximum capacity without hitting 100 C. If I max out both processors to 100% it doesn't get any warmer than 75 C.
  12. vv-tim macrumors 6502

    May 24, 2006
    We all know the heat is due to poor application of thermal paste... we've been through it all before :)

    And although it was a good try with the whole swap space theory, you're not taking one thing into account:

    - The CPU does the same amount of work either way.

    In one situation (more RAM) the CPU is able to get the work done faster -- and heats up faster -- but then it finishes and cools down. In the other situation, the CPU stays consistently at a warm state for the duration of the work. Both should have the same idle temperature EITHER WAY.

    I believe the temperature difference before/after RAM upgrade is completely circumstantially related to the RAM. It's possible that the thermal paste settled/hardened/became brittle after some time and that caused to heat change, or you just caught the machine at a good moment when you recorded the temperature beforehand.
  13. bill4588 macrumors 6502a


    Feb 2, 2006
    Kennesaw, GA
    mine stays 20-30 C when idle, but then goes up to 65-70 C when using a few apps. But when I'm watching videos it spikes up to about 78, and when I'm burning a CD is goes to about 82.....
  14. joebells macrumors 6502

    Oct 24, 2005
    vv-tim your line of thought is correct for idle temperature but I think most of us are talking about non idle temperature and if the processor is getting lots of little breaks then yeah it definately lowers the temperature it reaches.
  15. erikamsterdam macrumors regular


    Apr 21, 2006
    I already said it in another thread: put it in "better enery savings" mode and it will run much cooler. For surfing that is fine.
  16. alec macrumors regular

    Oct 19, 2005
    Washington DC
    A lot of people (and me too) that my computer gets a lot hotter when I'm watching Flash stuff or if I'm using FireFox (I couldn't tell you why, but it just is). If I avoid those two, I seem to stabilizing 60 to 65 celsius.
  17. ironic23 macrumors 6502

    Feb 8, 2006
    Like others have said, its also due to the hard disk spinning, etc. My MBP has been running really hot while running apps like Photoshop, etc. but when i'm just chatting or checking mail, i have it on the better energy savings and i do feel it running cooler.
  18. trainguy77 macrumors 68040

    Nov 13, 2003
    Also if your using your GPU alot it will heat up also. GPUs can create alot of heat.
  19. Senater Cache macrumors newbie

    Jun 6, 2006
    Ambient temperature, and your inability to control it.
  20. rugonnaeatthat macrumors regular

    Mar 2, 2004
    Adelaide, Australia
    my Macbook is just fine - I haven't measured the temps but it feels just like any other laptop. I find all the heat complaints really at odds with my experience.

    There was another thread somewhere that suggested that having two 1gb sticks made the macbooks run hotter than having 1gb and a 256 - basically saying that the bigger sticks were working as a plug for heat. There could be somehting in this.

    But I think the real culprit is what nobody is mentioning: Rosetta. It seems to me that rosetta can be really taxing on the cpu usage sometimes causing unusual pauses in photoshop for example on simle tasks where all the fans and cpu fire up for about 30 secs or so. Anyone had similar issues?

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