HP DL380e G8 fan noise
Your use of non-HPE disks is a cause because they're not reporting proper temperatures to the RAID controller.
The ILO controls thermal settings on this platform and the hysteresis curves that govern fan speeds.
I commissioned the work of a developer who wrote a machine-language hack that exposes ILO fan controls to the SSH command line. This will allow you to manually cut your fan speed.
Have fun. This will allow the use of the hardware you already have.