How to find the cause of a system crash? [Solved]

[BHReach]

I am getting intermittent system crashes. 2 types; 1 - system hangs, screen is blank, keyboard does not work, reboot; 2- system reboots itself. 1 could be an intermediate phase before the system reboots itself.

I have been using Sabayon Daily SpinBase and upgrading. I was using the daily from a couple of weeks ago, the problem was getting worse, i.e., more frequent crashes. Reinstalled yesterday with the current daily to see if that would fix the problem, no luck.

I looked in the log files but no clues as to the cause.

How can I determine the cause?

[BHReach]

I found the problem, failing memory (RAM). I had to go through the following rigamorole:

I tested the memory using Mem86+ and it tested bad.

I tried reseating the RAM sticks, switching sockets, running just 1 stick (4 GB) at a time. One of the sticks tests good, the other bad. I looked on the G.Skill (RAM manufacturer) support page and found a notice to AMD users to manually adjust the DRAM settings in the BIOS (what a PITA). I looked in the BIOS and the auto settings were wrong (the rated settings are 9-9-9-24, 1.5 Volt, 1600MHZ, the BIOS had 11-11-11-28, 1600MHZ. I further read that the most stable setting is 1333MHZ, 1.5 Volt, 8-8-8-24, which is what I set it to.

I ran the memory test for over 6 hours on the 'bad' RAM stick, in the 7th pass and still no errors when I stopped the test, it never got past the second pass without errors before I changed the settings. I thought everything was OK so I put both RAM sticks in and ran Mem86+ again. It took a long time but the RAM failed the test. I reseated the memory and ran it again just to be sure and it failed again.

It looks like the RAM kit is bad and I have to return it for replacement (G.Skill has a lifetime warranty).