why am I getting a boot failure when I set my Ram frequency to its 1866mhz rating?

[HugeGamma]

NOOB here

It allows me to change the frequency via "XPG mode" and I confirm via CPU-Z, appears to run fine.. but after every restart.. I get a boot failure message and defaults back to "optimal" 1333???

Do I need to adjust any other settings in the BIOS (timing/volatage)

2 ADATA XPG V2 8G 1866mhz
GIGA F2A88XXN
A10 7850k

please help, let me know if you need any other info

 

[Tradesman1]

Could be a couple of things, think I would change the DRAM voltage to 1.55 and try that, else we can raise the MC voltage