Macs fan control macbook pro which sensor pro#
The oft stated ‘fact’ that CPU A’s heatsink gets warm air from CPU B’s fan is nonsense propounded by dabblers who fancy themselves engineers – you will get the same differential with a cold Mac Pro as with a warm one, clearly disclosed in the above charts during the warming stage in the first few minutes of stress. The NB chip is the main ‘traffic cop’ which parcels computing labor out between the two CPUs and if you are wondering why CPU A always runs warmer than CPU B it’s that it also has additional traffic cop duties, so it works harder. Components at idle rarely exceed 115F with only the hot running Northbridge chip (with an operating ceiling of 220F) running at some 125-140F. Now during normal, low stress use, this is no big deal. The charts above are neither in error nor do they represent statistical anomalies. I have repeated the above measurements dozens and dozens of times on any number and variety of CPUs and the results are always the same. What was Apple thinking of – an increasingly common question when it comes to OS X? A cool electronic component is a happy electronic component. (Of course, thinking holistically, your Mac Pro gets warmer and you have to crank up the air conditioning ….) The result is that everything runs hotter (bad) with the sole benefit being that the fans run slower and hence quieter. What Apple has done in Yosemite is to set the OS to ramp up the cooling fans far later in the heat cycle than in Mavericks with the result that CPUs (and other cooled devices) get much warmer before the fans speed up, with the minor benefit that less energy is used at idle. These charts display the temperatures of both CPUs (orange and red) as well as the power supply (green) and ambient temperatures (brown) and are logged over a 70 minute cycle during which a stress test utility loads up the CPUs to near 100%.Īs you can see, the temperature chart for Yosemite differs dramatically from that for Mavericks (and indeed for earlier versions of OS X, not shown here).
Set forth below are two stress test charts from CPU upgrades I performed on 2009 Dual CPU Mac Pros:
My findings are based on over a hundred data sets and are statistically significant. One of the strangest changes was made in the transition from OS X Mavericks to OS X Yosemite (10.9 to 10.10) and it relates to how the OS manages cooling fan speeds. I have expressed my frustration at Apple’s seemingly mindless and unending tinkering with OS X before. Apple’s changes to fan management are a retrograde step.įor an index of all my Mac Pro articles, click here.
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