How is the new iMacs power consumption so drastically decreased? (-40%)

[Darajavahus]

If the only thing they did is update the CPUs (the GPUs are the same the X most likely doesn't mean anything) where comes from this major decrease in power consumption? (around 40%)

iMacs over time get a little bit more and more energy efficient,
last time that big jump came with a redesign in 2012,
21" 41.8W and 27" 78.9W vs 2011 85.6W and 140W
https://www.apple.com/lae/environment/pdf/products/archive/2012/imac_21.5inch_oct2012.pdf
https://www.apple.com/lae/environment/pdf/products/archive/2012/imac_27inch_oct2012.pdf
https://www.apple.com/lae/environment/pdf/products/archive/2011/imac_21.5inch_per_may2011.pdf
https://www.apple.com/lae/environment/pdf/products/archive/2011/imac_27inch_per_may2011.pdf
That's why I bought mine in 2012 coz from what I gathered I thought it was the most efficient desktop.

2010 92.8W and 149W
https://www.apple.com/lae/environme...Mac_Product_Environmental_Report_20100727.pdf
https://www.apple.com/lae/environme...ac_Product_Environmental_Report__20100727.pdf
2013 37.0W and 77.4W
https://www.apple.com/lae/environme...Mac_product_environmental_report_sept2013.pdf
https://www.apple.com/lae/environme...Mac_product_environmental_report_sept2013.pdf
2015 38.3W and 60.1W https://www.apple.com/lae/environment/pdf/products/desktops/21_5inch_iMac_PER_Oct2015.pdf
https://www.apple.com/lae/environment/pdf/products/desktops/27inch_iMacR5K_PER_Oct2015.pdf
Surprisingly 2017 gone up a bit 45.9W and 68.3W

https://www.apple.com/lae/environme...ch_iMac_with_Retina4KDisplay_PER_June2017.pdf

And now apparently 2019 just 27.8W and 39.0W!!!
https://www.apple.com/lae/environme...ch_iMac_with_Retina5KDisplay_PER_June2017.pdf

https://www.apple.com/lae/environme...nch_iMac_with_Retina4KDisplay_PER_Mar2019.pdf

https://www.apple.com/lae/environme...nch_iMac_with_Retina5KDisplay_PER_Mar2019.pdf

Both 2017 and 2019 reports state "Idle—Display on: System is on and has completed loading macOS. Display brightness was set as defined by ENERGY STAR Program Requirements for Computers, and Auto-Brightness was turned off. Connected to Wi-Fi."

2015 and earlier "Idle—Display on:System is on and has completed loading OS X; the display is set to its full brightness."

 

[jinnyman]

Probably more efficient power saving by CPU? Perhaps they also improved their firmware so that iMac can better utilize the components' power saving feature. That's only thing I can think of. Otherwise, they can manipulate the condition, but I doubt that.

I wouldn't really care that much since it's idle condition which I usually don't leave it in anyway. I either use iMac or let it sleep. The more important is the power consumption at load. That pretty much alone shows thermal issue for iMac.

I already use i9-9900k in custom built PC, and when loaded, CPU alone consumes around 200W without overclocking.(either 170 or 240, but I don't really remember)