Also try upping CPU vcore - I had to set mine manually fixed to 1.3v minimum for 3200mhz to work. Yes vcore is needed for RAM, along with SOC volts and DIMM volts...
If no good I would suggest running half the RAM and test out both sets of slots - the grey ones then the black ones and see if you can run 3200Mhz on the kit as it's advertised - joining two kits together like you have, is a bit of a gamble in my past experience... But hey its working at all - its probably some tweaking needed in some places.
You could try running this program - http://www.softnology.biz/ (Thaiphoon Burner) - and check some of the stats of your RAM, to check that all sticks really are the same.