Random reboots

[lp-void]

While using the system (Ubuntu 20.04) the system reboots with no apparent cause.
Never happened without using keyboard and/or mouse (e.g., doesn't happen at night).
Sometimes happens while just touching the mouse, but sometimes after 30 minutes of extensive use.

I built a custom kernel per these instructions: https://wiki.ubuntu.com/KernelTeam/GitKernelBuild
and the problem does not happen so far (over a day of work where before it happened at least every hour)

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: linux-image-5.4.0-40-generic 5.4.0-40.44
ProcVersionSignature: Ubuntu 5.4.0-40.44-generic 5.4.44
Uname: Linux 5.4.0-40-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.3
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC1: yakov 1952 F.... pulseaudio
 /dev/snd/controlC0: yakov 1952 F.... pulseaudio
 /dev/snd/controlC2: yakov 1952 F.... pulseaudio
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Fri Jul 17 10:40:52 2020
InstallationDate: Installed on 2019-10-21 (270 days ago)
InstallationMedia: Ubuntu 19.10 "Eoan Ermine" - Release amd64 (20191017)
IwConfig:
 lo no wireless extensions.

 eno1 no wireless extensions.
MachineType: System manufacturer System Product Name
ProcFB: 0 i915drmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.4.0-40-generic root=/dev/mapper/vg0-ubuntu--20.04 ro quiet splash nvidia-drm.modeset=1 debug ignore_loglevel
RelatedPackageVersions:
 linux-restricted-modules-5.4.0-40-generic N/A
 linux-backports-modules-5.4.0-40-generic N/A
 linux-firmware 1.187.1
RfKill:
 0: hci0: Bluetooth
  Soft blocked: no
  Hard blocked: no
SourcePackage: linux
UpgradeStatus: Upgraded to focal on 2020-06-19 (27 days ago)
dmi.bios.date: 10/24/2019
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 2606
dmi.board.asset.tag: Default string
dmi.board.name: ROG STRIX Z390-H GAMING
dmi.board.vendor: ASUSTeK COMPUTER INC.
dmi.board.version: Rev X.0x
dmi.chassis.asset.tag: Default string
dmi.chassis.type: 3
dmi.chassis.vendor: Default string
dmi.chassis.version: Default string
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr2606:bd10/24/2019:svnSystemmanufacturer:pnSystemProductName:pvrSystemVersion:rvnASUSTeKCOMPUTERINC.:rnROGSTRIXZ390-HGAMING:rvrRevX.0x:cvnDefaultstring:ct3:cvrDefaultstring:
dmi.product.family: To be filled by O.E.M.
dmi.product.name: System Product Name
dmi.product.sku: ASUS_MB_CNL
dmi.product.version: System Version
dmi.sys.vendor: System manufacturer

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This change was made by a bot.

[Kai-Heng Feng (kaihengfeng)]

Please attach `journalctl -b -1` after the random reboot.

[lp-void (lp-void)]

Problem no longer happens with kernel 5.4.0-42-generic.
all previous kernels do not have corresponding headers in the repository:
*Error! Your kernel headers for kernel 5.4.0-40-generic cannot be found.*
so problem cannot be reproduced and can therefore be closd.