In my experience a BIOS reset and/or adding/removing/moving the RAM modules around in the slots solves the "Hardware Reserved" issue that you had. So you solved it inadvertently by moving the RAM to the black slots. But there is no reason to keep the RAM in those slots.
The board you are running must use T-Topology rather than Daisy Chain, otherwise running the RAM in the wrong slots probably wouldn't work at all, at least not at full speed. In any case, now that the issue is gone you should go back to using the red colored slots because they will probably provide better stability. It's unlikely that the issue will persist.
As a side note, upgrading from 3000Mhz to 3200Mhz is not going to make a perceptible difference in performance. Furthermore, you might even have been able to OC your original RAM to 3200Mhz, which would have gotten you that small amount of extra performance for free.