I recent bought this motherboard, CPU, fan, RAM etc combo listed here https://www.ebay.co.uk/itm/122919127758
I’m running it with a Nvidia GTX 970 which I’ve had for a while and I’ve not no issues with. This issue has happened a few times on both 17.10 and 18.04 so I don’t think it’s software related, but please correct me if anyone thinks otherwise. I did a complete nuke & pave upgrade when going from 17.10 to 18.04.
From time to time (usually when returning to the computer after leaving it an hour or so idling) it freezes. It does so on rare occasions 4 or 5 times in total) and I’ve not found a way to reliably replicate the issue. I sometimes have control of the mouse but everything else is frozen, sometimes it just hangs on a plain black screen.
My gut was telling me that it was a overheating issue, but after putting temp sensors on my panel, I can see that the last time it froze, the CPU was around 35 degrees C.
I remember having a similar issue years ago and I only managed to solve it after upgrading the motherboard and CPU with leads me to suspect the motherboard might be faulty, but that’s not a confident suspicion.