Playback in Adobe Premiere causes my home computer's fans to go crazy. While the fans during playback on my work computer make no noise

Home computer specs:

• iMac (27-inch, Late 2015 with 5K Retina Display)
• OS X El Capitan 10.11.4
• 4.0GHz quad-core Intel Core i7, Turbo Boost up to 4.2GHz
• 16GB 1867MHz DDR3 SDRAM - two 8GB
• AMD Radeon R9 M395X with 4GB video memory

Work computer specs:

• iMac (27-inch, Late 2013)
• OS X Yosemite 10.10.5
• 3.5 GHz Intel Core i7
• 16 GB 1600 MHz DDR3 - two 8GB
• NVIDIA GeForce GTX 780M 4096 MB

I use Adobe Premiere CC 2015 on both computers, and use both to edit hi res footage. But during playback on my home computer my fans often get up to 2200rpm. Whereas on my work computer the fans remain inaudible unless I'm rendering for an extended period of time, or exporting. The temperature of everything on both is similar, yet my computer is the one that gets loud. It's hard to concentrate on editing with the fans accelerating every time you scrub through footage. What gives? I know my GPU at home is currently not on Adobe's recommended list (https://helpx.adobe.com/premiere-pro/system-requirements.html), but would it really make that big of a difference? Is there something wrong with my computer's fans?