ga-ax370 k5 and DDR4 (HX426C15FBK2) power up failure

[MrRicciolo]

Hi,

sorry for my english.

I can't run those DDR4 (HyperX HX426C15FBK2/16) at full speed.
They are on certified DDR4 memory list for my motherboard (ga-ax370 k5). Mobo have the latest F3b bios.
Memory are running fine @2400 but if I try to set XMP profile (@2666 that is officialy supported), my pc starts to loop power up and shut down. I can do nothing (neither enter on bios). The only thing I can do is to reset bios with the dedicated jumper.
I'm not sure, but with the old bios, they run @2666 if I remember well. I know that is not a big difference from 2400 to 2666 and this isn't a big problem (except the "shut down - power up" loop that scaried me ) but, if I have to be honest, this card disappointed me.

EDIT: I tried to downgrade the bios to F2. XMP profiles works (DDR4 @2666)

[BoNfiRe]

Don't use XMP and set it manually. I've got my RAM running @ 3200Mhz stable and it's only rated @  3000Mhz. If I use XMP, using the exact same settings, it won't boot.