Is he on AMD or Intel. Try one RAM stick at a time if you get 16GB on each in dual channel then your RAM is fine. Something fishy is going on and I think a BIOS firmware update or updates will really help in your situation. Don't make it to complicated. You had 2133Mhz RAM 16GB Kit and now with a 32GB kit you can only recognize one of the slots with it in. I think you have two options. Forget X.M.P because it doesn't work half the time. Go and change the voltage on the RAM Kit in voltage settings in BIOS. First see what the stock voltage of the Vengeance kit is then increase it so if its 1.35v increase it to 1.4v and save exit and see if it recognizes all 32GB in dual channel of course. If you put RAM side by side you run risk of running in single channel and that can hinder performance. After you set the voltage go to memory timings and input in what the stock timings are for each channel or each RAM stick. Then save and exit BIOS and see if your rig sees all 32GB also you must change the speed manually I forgot to say to 3200Mhz. Good Luck and let me know.