iMac 27" 2020 Rattling Noise (Possibly the fan?)

I've tried researching this online but there wasn't a definite answer for the problem. Some people said SMC worked for them but I tried it and it didn't help. I purchased an iMac 27" 2020 and it arrived 3 days ago. I opened it, started using it, but as time passed, I noticed this strange rattling sound (it sounds similar to a motor running). At first, I thought it was the external hard drive I had plugged in, but then I realized it was ejected and when I unplugged it from the computer, the computer was still making the noise.

The only time the sound doesn't happen is when the computer is asleep and obviously, when it's shut off. It doesn't happen during startup or the first minute when logging in. It just slowly starts coming up. My boyfriend has a iMac 27" from 2019 and his doesn't make this noise at all. Neither did any of the 6 MacBook Pros I've used the past 5 years (if this is even comparable). I also didn't notice this noise initially when setting up the iMac on the first day because the iMac was pretty quiet at the time.

I'm also not doing anything on the computer that requires high resources. I just have 10 tabs open on Safari, using Messages, Mail app, and Finder. My 5-year old MacBook was able to handle this fine and completely silent. I don't expect the iMac to be completely dead silent, but I didn't anticipate to hear this rattling motor sound even with an active music studio room on the other side of my wall and while sitting "regular" distance away from the screen.

Specifications:

OS: MacOS Catalina (10.15.7)

Processor: 3.8 GHz 8-Core Intel Core i7

Memory: 72GB 2667 MHz DDR4

Graphics: AMD Radeon Pro 5500 XT 8 GB

Storage: 2TB SSD

Any suggestions would really be helpful. I'm trying to go all routes before having to return this because it's really big, heavy and I don't have access to a car.