How to enable SATA hot plug / hot swap on T5610?

Hello!

I recently upgraded from a T3400 to a T5610 workstation.  I am running Ubuntu 16.04 LTS.  With the T3400, if I enable the all the SATA drive ports in the BIOS, I am able to hot plug/swap SATA drives to the unused ports while the computer is running.  I can plug in a drive while the system is running, and the drive will be recognized by Ubuntu.  I can unmount and plug in another drive, and that drive is recognized as well.

However, with the T5610, this doesn't seem to work.  In order for a drive to be recognized, it has to be plugged in before the computer boots.  On the T5610, I have the latest BIOS, SATA set to AHCI, and I have all of the SATA ports enabled.  If a drive is not plugged in during boot, the drive is not recognized when it is hot plugged.  Ubuntu doesn't seem to recognize that anything is happening. 

I basically cloned my T3400 Ubuntu drive and plugged it into the T5610.  Everything seems to be working fine, except the SATA hot plug / hot swap.  This leads me to believe that the BIOS is somehow preventing this.

I did not find any settings in the BIOS that would control this.  Does anyone know if the hot plug / hot swap should work on the T5610?  If so, what might be needed to make it work?

Thanks!