Good work on the System Specs.
Do you still have the stock PSU?
OEM PSUs are not known for their quality or longevity.
I just had to replace one in a +4 year old Dell desktop.
What is the Intel RST driver version?
In Control Panel > Power Options, is it set to 'Balanced'?
Log Name: System
Event ID: 55
User Name: NT AUTHORITY\SYSTEM
Processor 0 in group 0 exposes the following power management capabilities:
Idle state type: ACPI Idle (C) States (1 state(s))
Performance state type: None
Nominal Frequency (MHz): 1800
Maximum performance percentage: 100
Minimum performance percentage: 100
Minimum throttle percentage: 100
Do you have EIST (SpeedStep) enabed in your BIOS?
Let us know the memtest86+ results.