Reducing 2017 5k iMac i7 fan noise

wardie

macrumors 6502
Original poster
Aug 18, 2008
426
136
I tried an interesting experiment yesterday during a big Lightroom batch process which ramps up the CPU load on my i7-7700K 8 virtual cores with hyper threading, normally causing the fan to become noisy and max out at 2700rpm.

I just switched off the turbo boost. This had the effect of maintaining an ongoing much quieter operation with the fan at between 1200-1800rpm whilst still loading the cores 100%. CPU temp dropped a bit to around 90-93C.

As I’m not doing it for the money and don’t actually care about every last second (who really does?) then actually a 5% hit on processing time was reasonable to me for the sake of a much quieter machine I could sit at and still use to surf in parallel without it sounding like a jet engine. Core temp was still just over 90C which isn’t exactly cold but within its limit (maybe not to some people’s tastes, in which case get a different chip).

On = 4.4 GHz 97-98C fan 2700rpm
Off = 4.2 GHz. 90-93C fan 1200-1800rpm
Tools = iStat, Intel Power Gadget, Turbo Boost Switcher (free version)
 
Last edited:

mikehalloran

macrumors 68000
Oct 14, 2018
1,750
448
The Sillie Con Valley
Since Photoshop and Lightroom can bring the most robust computers to their knees, I think you found a good solution.

Do you have an SSD or Fusion drive? How much RAM are you packing?
 

wardie

macrumors 6502
Original poster
Aug 18, 2008
426
136
Since Photoshop and Lightroom can bring the most robust computers to their knees, I think you found a good solution.

Do you have an SSD or Fusion drive? How much RAM are you packing?
1TB factory internal SSD (O/S plus some Lightroom classic CC catalogue & masters for working on), plus a USB3 HDD on the side for bigger media. 24GB RAM = 8 GB original Apple + 16GB upgraded.
 
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