As expected, this is a long standing issue with Dell firmware. From their own documentation for previous generation servers- A system configured as non-RAID has a higher noise level than a system configured as RAID. With non-RAID, the temperature of the hard disk drives is not monitored, which causes the fan speed to be higher to ensure sufficient cooling resulting in higher noise level A bit of Googling shows the problem has only gotten worse with the next generation of tower servers having low quality, noisy fans and still don't allow a negative fan offset in situations like this.  
Hi all, I swapped storage controllers from H730p to HBA330 in a T630 after which the fan speed ramped to 55% PWM max (around 3k RPM).  Server has been running for around a year with H730p and same HDD combination with no issues and near silent performance. No other hardware has changed. All firmware is up to date- BIOS is 2.13.0, iDRAC 2.82.82.82, HBA330 16.17.01.00 Drives are 8 x Dell P/N W0VNC (TH0W0VNCSGT008BC00C8A00) with latest EA04 firmware Thermal profile is `Minimum Power`. Changing to `Default` doesn't change fan speed. Fan Speed Offset is `Off`. Minimum Fan Speed is `Default`.  Removing all hard drives causes fan speed to return to normal. System has no active alerts. I've switched back to the previously working H730p but high fan speed remains. I've also unplugged all power + held power button for 20 seconds before powering on and gone through retire + repurpose wizard to clear all iDRAC and BIOS settings but issue remains. Any advice would be appreciated!
T630 fan speed high after RAID controller replacement