I bought 7 fans for my mining rig. They are very good in terms of airflow. However, they are quite noisy, like an airplane. The build quality is mediocre because after 3 months, 2 of them started whistling. They serve their purpose for the job I bought them for, but I wouldn't recommend them for a PC.

Because it is powered by a (4-pin) molex, it necessarily operates at maximum speed and obviously cannot be adjusted from anywhere because it directly draws power from the power supply. So yes, it is noisy.
But still, if we compare it to a pwm at 100%, it still makes noise.
Also, the blades are fragile - I accidentally touched the fan with my nail while it was spinning and one blade broke immediately. While in other brand fans, in a similar incident, they immediately shut off and no blade broke.
Finally, the airflow is very satisfactory, even amazing! Very positive impressions about the airflow!
But at this price, for a server, for a PC in a remote room, it is fine.