Here is the story.
After working flawlessly for 3 months....
While rendering a video the system totally freezes. Only way out power off and on.
On restart system will not post. Stays on 00 does not move.
Re-seat CPU. Same problem
Use Flashback to re-flash Bios.
System posts but hangs on code 62
Re Re-flash
Same outcome
Try various memory combinations. Same outcome.
Here is where it gets interesting;
Remove GFX card and move it to lower PCIe 16X slot
System posts and boots.
Move it back. System hangs on 62.
Lower slot again and working perfectly apart from occasional 100% fan spikes.
( I monitored them and could see not temp rise via Aurus and CPU via other software)
I pulled an old GFX card from another system. An Asus DirectCU II R9 270X. And it worked in the top slot perfectly. So it seems to be the 1080 not the board? It does look very much like a GPU problem rather than the board or CPU.
Just to see how much worse speed wise it is than the 1080 I ran cinebench. Result: It out performed the 1080 in both CPU and GPU scores
Is this a known problem ?