ProLiant ML350p Gen8 - System Fans constantly stepping up to 100%

This school's ProLiant ML350p Gen8 Server, has been a godsend for some years, and now recently, over the last 6 months has changed to deafening anyone nearby with jet engine sound effects as the fans ramp up to 100%
iLo shows absolutely no issues, and everything A-OK ... including temperatures which for everything are nowhere near 'Caution' temps}
The server lives in a small Air Conditioned room at a sustained low temperature also.
Ive updated everything i could think of and performed a physical examination inside the server case, and can see nothing that may be causing said issue...
If i reset iLo (under diagnostics) the fans return to nearer their normal speed around 10% ... however this progressively steps up 1% at a time to around 30% and from there steps up in 4% speed intervals ... ultimately resulting in a deafening 100% fan speed on all 3 internal fans..
So loud that its disrupting teaching in the IT suite that the server room is within etc.
Any advice or support would be welcomed.