Gobsmacked: Power Efficiency of the 2017 iMac 5K vs 2015 iMac 5K, Particularly on the Road in Sprinter Van
Recently I bought a 2017 iMac 5K for solid reasons.
See also Using Two Thunderbolt 3 Ports to Build Out a System and Options for Connecting a Display with Mini DisplayPort or DisplayPort input to a Mac with Thunderbolt 3 / USB-C.
One significant concern was an increased power budget including the need to use an OWC Thunderbolt 3 Dock in order to connect my NEC PA302W wide gamut display (the Dock supplies the necessary Mini DisplayPort port).
My thinking was that if the Dock chewed up another 10-20 watts, this would reduce on-the-road battery life in my Mercedes Sprinter photography adventure van (see the desk layout in my Sprinter van).
I need not have worried, in fact I was gobsmackked by a power savings with the 2017 iMac 5K, even with adding the OWC Thunderbolt 3 Dock, which consumes power of its own. The results were stunningly favorable: my runtime has increased*, not decreased:
2015 iMac 5K alone, idle with lit screen: 60 watts AC
2017 iMac 5K alone, idle with lit screen: 48 watts AC
2015 iMac 5K + NEC PA302W 142 watts AC
2017 iMac 5K + Thunderbolt 3 Dock + NEC PA302W = 122 watts AC
OWC Thunderbay 4 TB3: 24 watts AC with 4 idle but spinning 12TB drives
Wow! Even adding the Dock, the configuration with the 2017 iMac 5K draw 20 watts less power. Sweet.
Presumably the 2017 iMac 5K not only draws less power overall (CPU, memory, etc), its GPU must be more efficient also, taking less power to drive the external display. I’m psyched.
Assuming average power consumption (idle + active usage) of 200 watts @ 12V DC draw on the battery, and drawing the battery down by 90% (10% reserve), I can run for 23 hours without any idling alternator charging (5120 watt hours X .9 / 200 watts = 23 hours). Not bad! See RV Electrical: Calculating Realistic Electric Load.
* All figures above are AC power; add 30 watts for power inverter overhead for DC power draw, which is what really matters to how long the 5 kW battery will last.
Configuring the 2017 iMac 5K as a system
See Switched to 2017 iMac 5K as Primary Machine: Details on Gear I’m Using.
Below, the storage for home and travel:
The iMac 5K along with the NEC PA302W and the Apple Thunderbolt 3 Male to Thunderbolt 2 Female Adapter.