There’s 20 some odd threads on this forum about the loud fan in the power supply. That’s “normal”
Here’s my fix: Exteme loud power supply fan - #7 by brent113
As a matter of terminology for what’s about to follow, this is the power supply, and there are 2 fans inside. The first, more readily accessible one is the ‘enclosure’ fan, and then inside further there is an off the shelf power supply module that has another internal fan.
In the off chance it’s not the enclosure fan being a problem, you could open it up and unplug the first fan and see if the problem goes away. If it does, then the above linked fan replacement will fix the issue.
If that does not fix the problem then it’s the actual power supply fan having a problem, and that’s not as readily replaceable. If you are under warranty probably ask for a replacement power supply in that case.
Some experimentation by some others have indicated the power supply’s internal fan is sufficient for cooling, and the case fan at the rear is kinda just a bonus. At least a couple people have just unplugged the case fan and not even replaced it. Probably not recommended though…