Why does the iris pro run hotter then the 750M?

Discussion in 'MacBook Pro' started by richard371, Dec 29, 2013.

  1. richard371, Dec 29, 2013
    Last edited: Dec 29, 2013

    richard371 macrumors 68020

    Feb 1, 2008
    I decided I didn't really need the 750m so I disabled it and am using the iris pro only. I just ran plane 10 bit and istat reported the gpu at 180 which is even hotter then the 750m. If the 750m is off why is it getting so hot?
  2. yjchua95 macrumors 604

    Apr 23, 2011
    GVA, KUL, MEL (current), ZQN
    I think it's because when you use Iris, you stress out the processor also, so the processor has to work harder.

    When you use the 750M, you don't stress out the processor as much, so it brings the average temperature down.
  3. richard371 thread starter macrumors 68020

    Feb 1, 2008
    Thanks. Was looking at your sig. Do you currently have that many computers lol?
  4. leman macrumors G3

    Oct 14, 2008
    Is this fahrenheit or celsius? ;) If fahrenheit, there is nothing to worry about, its a pretty normal temperature under load. If celsius, either your sensor or the software is broken.
  5. richard371 thread starter macrumors 68020

    Feb 1, 2008
    F of coarse. God I wish the US would switch to the metric system. Im embarrassed that I still use F, pounds, miles, inches etc.

  6. yjchua95 macrumors 604

    Apr 23, 2011
    GVA, KUL, MEL (current), ZQN
    Not all are mine :p it's a mix of mine and my dad's. He needs the Mac Pros for his work, only God knows why on earth would he need 12 cores and 64GB RAM. All I know is that he does a lot of heavy rendering.

    I only use the 15" Sandy Bridge, 15" rMBP Haswell and the two iMacs :)



    I still have no idea why the US is still using the antiquated Imperial system. It can be disastrous sometimes.

    Remember that time when an Air Canada Boeing 767 ran out of gas and landed at an abandoned airfield? Turned out that the ground crew refueled the plane in pounds instead of kilograms. They were so used to refueling in pounds, and the 767 was the first Boeing aircraft to use the metric system.
  7. richard371 thread starter macrumors 68020

    Feb 1, 2008
    I think we need a protest in America to ban the imperial system. I can't believe we are raising our kids on this system. I mean we have it made as far as languages go.

  8. simon48 macrumors 65816


    Sep 1, 2010
    Fahrenheit is soooooo stupid! The only pro I can think right now of for the entire imperial system is 12 inches can be evenly divided into thirds.
  9. richard371 thread starter macrumors 68020

    Feb 1, 2008
    so in the rest of the world is it a 13" and 15" MBP lol?
  10. yjchua95 macrumors 604

    Apr 23, 2011
    GVA, KUL, MEL (current), ZQN
    Well I guess we'll have to wait and see. There was a proposal to metrify the US, but so far everything's still in the imperial system.

    Early in 2013 a bill was introduced by state Representative Karl Rhoads of Hawaii that seeks to make the metric system mandatory within his state.

    If this bill is passed and goes into effect by 2018, Hawaii may very well be the first US state to entirely use the metric system.

    I grew up in the metric system, but I have no problems using imperial units, although it may be a tad bit inconvenient for me. Personally I prefer the metric system, because everyone else in the world uses it.

    I took my SAT Reasoning test and subject tests earlier this year, and was glad to see that everything was actually in metric units. Maybe it's a start.


    Yeah in the rest of the world, we still measure screen size by inches *scratches head* Probably because the first PCs came from the US.
  11. Swampus macrumors 6502


    Jun 20, 2013
    And that would be exactly why he needs 12 cores and 64GB RAM. ;)

    President Ford signed the Metrics Conversion Act in 1975. President Carter loved it and picked up where Ford left off and finished setting up the USMB. The Reagan Administration determined that it was a liberal conspiracy and crushed the whole thing in 1982. I suspect that such a movement would be even less likely to succeed now. At the moment, some states appear to be unsure that science should be taught in schools.

    In France, it is known as a Royale With Cheese.
  12. dusk007 macrumors 68040


    Dec 5, 2009
    Inches and sometimes feet are the only imperial measurements that still show up often in brand names. I think it is because the numbers are sometimes smaller and easier to handle and everybody sort of knows what it means.

    Farhenheit is imo an all around weird measurement. Why that stays around I don't get. The weight measurements are also really annoying if you actually have to use them on a daily basis. The smaller ones for cooking, I could deal with lb but oz :( And the volume measurements. I would rather measure in a beer glass based system than what the US does.

    @op. One chip all heat means that that chip gets hotter than if the heat is spread over two chips.
  13. thundersteele macrumors 68030

    Oct 19, 2011
    This would also be my guess. If everything is done on the CPU die, it is not surprising that it runs a bit hotter than when the load is distributed evenly.

    I am not sure which temperatures are reported. On my 2011 15'' MBP there are CPU and GPU temperatures. However the GPU temperature always is that of the discrete GPU, the iGPU has no separate sensor. What tends to happen is that the GPU sensor reports weird numbers when the GPU is not active... often it reports negative or at least below room temps.

    So if the 180F are measured on the dGPU while it is not active, that would be weird... if it is just the CPU temperature then fine.
  14. ha1o2surfer macrumors 6502

    Sep 24, 2013
    The Iris Pro GPU uses less voltage than a CPU does so it actually should produce lower temps then just a fully loaded CPU. Also, temps should not be an issue because no matter what the CPU/GPU is doing, it needs to stay under it's power limit. So if the GPU is being stressed the CPU can't run full bore as well.
  15. dusk007 macrumors 68040


    Dec 5, 2009
    In very few cases the CPU runs full bore while the dGPU is stressed.

    If you have two cups of cold water and one cup of boiling water. If you mix the boiling water half half with the other two those won't be as hot as if you mix the whole cup with only one cold cup.
    The iGPU also runs on 55W TDP when the dGPU is off at least I measured that on mine.

    If you only stress the CPU with no GPU load, regardless which CPU is active you quickly hit very high temps and high fan speeds. The MBP isn't actually good at handling full load on both.

    Anyway if the dGPU reports some temps while inactive it probably hasn't cooled off. Also since both hang on the same heat pipe the cpu will heat the dGPU in a way if the temp delta is such that the die is actually cooler than the heatpipe.
  16. kurzz macrumors 6502


    May 18, 2007
    In Canada, we buy 33 and 38 cm laptops. :p
  17. MacPioneer macrumors member

    Oct 26, 2010
    I'm still getting used to hexadecimal, since octal in the IBM 70xx series and DEC PDP series were obviously the way God intended us to think about computers :)
  18. alphaod macrumors Core


    Feb 9, 2008
    The computer industry (even in the US) mostly uses metric. I always use metric for computer temperatures, but my understand is mostly relative. That said Fahrenheit is more precise measurement.

    However I see a lot imperial use around the world; here we have displays (monitors, TVs). For some reason tire diameters are measured in imperial, but their width is measured in metric (even in the US).

    Honestly if someone told me the weather and told me the current temperature in Celsius, I would need to convert it in my head to Fahrenheit to know if it hot or cold.

    Anyways 180 degrees Fahrenheit isn't that hot for a computer.
  19. dusk007 macrumors 68040


    Dec 5, 2009
    And if you were used to metric it would be the other way around. With metric you always know where freezing temp is and where boiling temp is. F tells you where body temp is which isn't all that useful most of the time. Not even for telling hot from cold weather because below 100F is still really hot even if it is dry heat.
    I found F to be really hard to adjust to because there is just no useful thing (like 0C/100C) to hold on to when you try to guess the right temp for cooking and stuff. I would rather use Kelvin.
    At what temp does it snow in F, what temp is boiling water. It all seems rather arbitrary. Celsius is just Kelvin adjusted so much to get reasonable measurements in a world filled with water and carbon based creatures that are mostly water.
    You can add one decimal after the comma/point to get a three digit temp but I doubt that is ever useful. To say Fahrenheit is more precise than Celsius is like saying cm is more precise than inches. :D

    Still by far the weirdest measurement I came across in the US is for volume. Fl.oz.???? Why not just use liters everywhere? Sometimes you do seem to use liters and other times is completely wonky fl.oz.
    Americans just like it complicated :D

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