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Cascader

macrumors newbie
Original poster
Nov 30, 2015
2
0
I'm considering a new iMac purchase, and trying to find out Idle and Max Power consumption for a couple of different configurations - i5 3.2GHz M390 (2GB), and i5 3.3GHz M395 (2GB). I realise amount of installed RAM and differing storage options (e.g. SSD or Fusion) will have some effect, but CPU and GPU account for the lions share of power use under load.

Apple has a useful page here, but lists only one Late 2015 27" configuration.

i7 4.0GHz M390
Idle 63W, Max 240W

That's a start though, and enables a quick calculation: Intel lists the i7 TDP as 91W, and the i5 TDP as 65W here. That's a difference of 26W, so I can estimate a lower configuration:

i5 3.2GHz M390
Idle ??W, Max 214W

Unfortunately without knowing the TDP of the two graphics cards (M390 2GB vs M395 2GB) I can't estimate power consumption for higher configurations.


Does anyone know how much power the i5 3.3GHz M395 iMac uses when idle, and under full load?

Or alternatively, does anyone know TDP or how much power the M390 2GB and M395 2GB graphics cards can pull, as used in the iMac?
 

maflynn

macrumors Haswell
May 3, 2009
73,419
43,307
I'm curious to know what, what would be the value of knowing this?
 

Cascader

macrumors newbie
Original poster
Nov 30, 2015
2
0
Thanks for the info Crusin. That suggests (potentially) an extra +25W under load moving from the 3.2GHz with M390 to the 3.3GHz with M395.

what would be the value of knowing this?
Good question!

The lower the power consumption the cooler, quieter, cheaper and more environmentally friendly the system is to run.

Apple's page here shows that the amount of power consumed translates directly into the amount of heat produced. When power consumption increases by a factor of 4, heat produced also increases by a factor of 4.

This information is valuable if you're concerned about excess heat, work in a quiet environment sensitive to fan noise (e.g. audio editing), would like to keep your carbon footprint down, or happen to be the poor soul who pays the electric bill. Knowing the Idle and Max power consumption of the different configurations on offer makes for a more informed purchase decision.

If anyone can share some actual power consumption figures for a 3.3GHz with M395 (or even a slightly different configuration) that would be great.
 

maflynn

macrumors Haswell
May 3, 2009
73,419
43,307
Fair enough, I guess that thought process had not really entered into my mind or purchase matrix. Good to know though :)
 
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