Thank you Preston
Sometimes combining two memory kits with the same specs works without issues and sometimes it can give you problems which could be happening here.
Fist thing I'd try is, at the very top of the Dram Timing Control page set Maximus Tweak to Mode 1.
Maximus Tweak Mode 1 - helps with compatibility
Maximus Tweak Mode 2 - helps with overclocking
If that doesn't help, try setting your ram manually with these settings and see if this stabilizes things.
Dram Frequency - 3200MHz
Dram voltage - 1.40v
CPU VCCIO voltage 1.15v - 1.25v
CPU System Agent voltage 1.15v - 1.25v
Enter the primary timings at the top of the Dram Timing Control page. There are four timings but you will enter three numbers as the middle two are tied together, for example if your primary timings are 15-16-16-36 -2T
Command Rate 2N.
F10 and Enter to save and Exit.
If this doesn't help, try each 16GB kit separately to confirm there are no issues.