Power consumption and thermal output information for iMac computers
https://support.apple.com/en-am/HT201918

iMac (Retina 5K, 27-inch, Late 2015)
27-inch Retina 5K display, 4.0 GHz Intel quad-core Core i7, 32GB 1866 MHz DDR3L SDRAM, 3TB Fusion Drive, AMD Radeon R9 M390 with 2GB GDDR5
電力消費 Idle　63 W　CPU Max　240 W
熱出力 Idle　215 BTU/h　CPU Max　819 BTU/h

iMac (Retina 5K, 27-inch, Mid 2015)
27-inch display, 3.3 GHz Intel Core i5, 32GB 1600 MHz DDR3 SDRAM, 3TB Fusion Drive, AMD Radeon R9 M290
電力消費 Idle　70 W　CPU Max　197 W
熱出力 Idle　239 BTU/h　CPU Max　673 BTU/h

iMac (27-inch, Late 2014）
27-inch display, 4 GHz Intel Core i7, 32GB 1600MHz DDR3 SDRAM, 3TB Fusion Drive, AMD Radeon R9 M295X 4096 MB
電力消費 Idle　70 W　CPU Max　288 W
熱出力 Idle　239 BTU/h　CPU Max　983 BTU/h