As per your PM, on that board, it should not ever change from Quad channel to triple channel, unless something is wrong, to the best of my knowledge.
Did you change back the memory voltage to the stock value? If not, go ahead and do that since increasing the voltage did not help the problem before.
In fact, if you like, it might not be a bad idea at this time to completely reset the bios by removing the CMOS battery again. It means you will need to go back in an reconfigure any preferences you had set before that you want configured a certain way.
Many changes as we've made, it wouldn't be a bad idea to do that, then set the memory to the XMP profile as you had it originally. See if it goes back to quad channel.
Seems suspicious though.