Usually when there is memory issue, your PC won't even boot-up, not crash after hours.
As suggested above by Burnin, run a memtest, ideally overnight.
Mixing memory is never best idea, though it often works fine. With overclocked memory (which 3000Mhz is), you might ought to set them up manually, esp. since they have different timings. Solution in that case is to relax the faster (CL15 in your case) memory to match the slower (CL16).
Always run latest UEFI for best memory compatibility. It's something manufacturers constantly improve.