Error at boot:
942-Memory Training Error.
DIMM 5 on CPU 0 experienced an error during training (CODE 3015)
Fix
Go to BIOS Setup (F10)
Power tab
Select OS Power Management -> change 'Idle Power Savings’ from ‘Extended’ to ’Normal'
Select Hardware Power Management -> check ’S5 Maximum Power Savings’ must be in ‘Disabled'