GA-AX370-Gaming K7 - auto BIOS reset - Any ideas?

[absic]

So, I have been running my GA-AX370-Gaming K7 with BIOS F10 quite happily for over a year. This morning, without any reason that I can find, it reset the BIOS to its default values.

I haven't changed any hardware or done any tweaking since last year and am at a loss to understand why this should suddenly happen. Anyone have any ideas?

CPU: AMD Ryzen 1800X
RAM: 4 x 8Gb Corsair Vengeance at 2,400Mhz
GPU: Nvidia Geforce GTX 1050ti (silent version)
Windows 10 64bit Pro - latest updates installed

1 x 500Gb Samsung M.2 PCI-e drive
1 x 250Gb Corasir SSD
1 x 250Gb Sandisk SSD
1 x 1TB Seagate HDD
1 x Pioneer BD-RW (BDR207M) Drive

Logitech wireless keyboard and touchpad
Roland Duo-Capture EX USB Audio Interface (Not active at boot)
2 x Logitech 920 Webcams

Ultrafast BOOT set in BIOS

The PC is water-cooled (bespoke system) and the CPU rarely goes above 40C and usually runs at between 28C - 35C

[shadowsports]

Hi Absic,
I'd check the MB battery, the power supply and disable ultra fast boot.  Then again, if the battery and PSU checkout, you won't likely see this again unless there was a severely power fluctuation. 
 

[AgentFXA]

Probably there is an overclock the bios no longer likes hence reset?!
Try all defaults/auto and see if the problem goes away ... then start from there to find the culprit

[absic]

Thanks Shadowsports and AgentFXA. 

The things you mention are things I have already looked into, which is why I am puzzled by this one.

I know, it's a computer and computers do seem to have a mind of their own and sometimes, things happen that just have no explanation. 

[90Ninety]

I am having a simmilar issue with the same board but , with a 2700 , after installing a so called ' memory upgrade '  https://forum.giga-byte.co.uk/index.php?topic=22887.0

The computer will completely reset the CPU speed to default at every cold boot , unless I run it at stock speed . This only happens when  the enabling XMP profile on the Flare X memory . Does not happen with the Corsair Vengeance Memory - So much for B-Die 

The irony is that if I plough through the Cold boot instability a few times , the computer eventually runs stable  - until the next cold boot .

Really Weird !