Did not see one plate of RAM.

[Problem description]
Recently took Ryazan 1600s,mother asus prime b350 m-a and 16 gigs operatives m378a1g43eb1-cpb.The problem is that I dispersed the operatives from 2133 to 2600 and more than a month everything was fine but today morning I started the computer popped up the error of failing to disperse and disappeared in the BIOS 8 gigs operatives.Although the BIOS sees it but does not use.Changed the RAM sometimes it works on one run also works.In the BIOS set to the standard 2133 I get an error-system has POSTed in safe mode.This may be due to the presious attempt failing because of system instability, or if the power button was held in to force of the system .If the system failed to POST after .You made changes to the UEFI setting, you may wish to revert to stable settings to prevent POST failure . Press F1 to run setup