Hi Ced0016 welcome to this free user-to-user Alienware laptop discussion forum. 

If the Alienware m15 R3 (5/21/2020) was under Dell warranty, they replace the whole Fan and heat-sink assembly, not just the cpu/gpu fans. The parts-people database reveals OEM replacement Dell Part Number (DP/N) to be used to search the internet so that cpu/gpu replacement fans or the whole Fan and heat-sink assembly can be ordered. Alienware Laptop Notebook Replacement Parts (parts-people.com) There should be YouTube video showing how to replace both fans. Having watched the YouTube video, you might want this replacement undertaken for you, see $100 Dell Laptop Repair | Dell Repair | Laptop Repair | Notebook Service Center (parts-people.com).  

@crimsom​ Thank you for your response, I had visited and seen this video earlier, but the model of my Alienware (M15 R3) is not the same as the parts offered on the site/and on the video.

none of the replacement fans have the same serial number as the one installed on my Alienware, and the shape of the head-sink is really different.

@Ced0016​ thank you for sharing update. My bad. Did not find Alienware m15 R3 YouTube video on the internet and the Dell documentation does not show how to replace cpu/gpu fans. Please look for DP/N at Dell Alienware m15 R3 Fans | OEM Replacements (parts-people.com). Internet search found this m17 R3 YouTube video for how to replace the fans Alienware M17 R3 Almost Complete Disassembly SSD Hard Drive Upgrade Battery Fan Replacement Repair - YouTube? If removing the whole "Fan and heat-sink assembly", do not disturb any of the thermal pads. Dell do not provide thermal pad replacement information.