Exhaust fan speeds or MB Pro and iMac -- why the difference

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Got a 2010 iMac quad core i7 and a 2010 MB Pro intel core2 duo. Have istat pro on both.

Noticed when watching videos that the exhaust fan speeds on the two differ when watching vide online. The iMac can get up to 1300 rpm or so, while the MB pro stays around 2000 rpm much of the time.

Can anyone tell me what affects this? Often times the CPU doesn't get that hot (unless, it seems, I'm running Parallels while watching some videos. The iMac has some more fans as well, like a HD fan and cup fan, etc, as well as a GUP Diode and heatsink, while the MB Pro does not seem to have those things (or at least it's not listed in istat.

What exactly affects the temperatures or the fan speeds? Just curious and wonder if there's something I should be worried about. No changes to the hardware have been made in either, and I'm running Yosemite on both. I thought that the iMac fan wouldn't get that high (never seemed to do before).

Does the type of video being watched affect the temperature or the fan RPM?
 

pigoo3

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2011 17" MBP 2.2ghz, 16gig ram, OS 10.11.6
- Have you considered that an iMac and a MacBook Pro are totally different designs?
- Have you considered that the components in a MacBook Pro are much more closely "packed" than in an iMac?
- Have you considered that the fans in an iMac might be much larger & move more air at the same or lower rpm's than the fan in a MacBook Pro?

The ONLY discussion of this sort that would be logical…is if you had two of the exact same MacBook Pro models…exact same hardware configurations…and both doing exactly the same thing. Then a comparison of temps & fan speeds might be proper.

Making this sort of comparison is like comparing what an 18-wheel tractor trailer is doing versus a VW Beetle!;) NOT Comparable!

- Nick
 
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Silver M1 iMac 512/16/8/8 macOS 11.6
The iMac follows the laws of nature. When it warms up even without a fan, warm air would naturally rise out through the top vents whilst drawing fresh air in through the bottom vents. You can see therefore the fans in the iMac would need much less speed to increase the airflow, 1300rpm v maybe 2000rpm?
 

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