I have build a few hundred PC's over the last 25 years..

Sometimes a certain brand/type of memmory just gives troubles with a certain brand/type of motherboard. Either not running at all or generating random crashes.

When building a PC i only use memmory that i know will work because it is listed in the manual. Or because i know of a configuration with that combo of mainboard/memmory that is being produced and tested by a reliable company.

Offcourse its also important that you use only 1 type/brand of memmory.