There's probably an issue with the intel fan, and pwm responses not registering correctly, it's programmed specifically for the OEM dell fan.  I'd suggest swapping the Intel fan and replacing with the OEM Dell fan. 
  [IMAGE] When I am on auto mode (Alien Control) the CPU fans run at about 4840 rpm. When I am on manual mode (User Control) the CPU fan runs at about 750 rpm. I found these numbers on HWiNFO. This PC is Alienware Aurora R5 but due to several upgrades (GPU, CPU, new Drive, etc...) I have had to reinstall Alienware Command Center. I have only upgraded to things compatible with the original motherboard (I haven't upgraded the motherboard). I don't know why it displays the CPU fan as a CPU pump but I have ignored it up until now. What I want to find out is how to change the CPU fan as I can the front and top fan. Right now it is either too loud to bear or my CPU temps reach unhealthy heights. I'm trying to adjust to reach the sweet spot in between.
CPU fan speed not accessible in Alienware Command Center