I am trying to set the system up so it will adjust the fans based on the HDD temperatures. I don't think you need a fan controller.just better fan placement. More than happy to help you should you need assistance with fan placement or recommendations. I've never really had to worry about using a fan controller (hardware) outside of a gaming system.so if you're having issues, you should rethink your fan positions in your case. Larger fans (120mm or 140mm) push a bit more air at lower RPM's and in my case, it reduced the noise level of the server while dropping the temperature.

This causes all my air flow in the hard disk section to be segmented away from the CPU side.all of my disks dropped about 10 degrees. I then put in a bunch of HUGE fans.one pushes, one pulls.on the hard drive side. I bought a new case.a Fractal Design Node 804.this case splits the motherboard/CPU/GPU from the Hard disks. I can tell you what I did to reduce my HD temperature. Keep in mind that you set these items in BIOS for profiles.and generally, fans will increase their speed based on temperature automagically. Plenty of options for hardware fan controllers but I don't think you need one. Ive seen it go up to 47 degrees during Parity Check. Generally the HDD stays within 30-40 degrees Celcius on a warm day. Can you offer some suggestions? The only time I have seen the HDD temp go up is during a Parity check. Is there something I can purchase to add to my system? I'm not that knowledgable about how the system can get the HDD temp to control the fan speed.

Asus motherboard fan speed control