What iDRAC FW you have on the server? Is there any recent changes done on the server like FW update. There is reports of similar issues on similar 14G servers with latest iDRAC FW. You can refer below post for details [URL] 
Hi there,  Two years ago the photography studio I work in started using a Dell Poweredge T340 to backup photos and video.  Yesterday morning when I came into the office the fan was running incredibly loudly. I spent a long time speaking to someone at Dell Support but because none of the logs show any issues they can't do anything.  The idrac is not showing any warnings, and the environment that the server is in hasn't changed, and we have never had this issue before. The fans are running at 89% PWM.  Can someone please advise how we can get the fans to be quieter? They are extremely loud.  Thanks!
Loud fan on Poweredge T340