Question Sudden semi-random shutdowns/restarts. No blue screens, no errors, no logs, no dumps, nothing.

Sep 24, 2019
Problem description:
My computer has been shutting down randomly for a while now. I think for more than two years it randomly shut down every so often, but not more than a few times per week (and I use it for work, uni and entertainment, so it runs for 100's of hours per week), which never bothered me enough to figure out the cause. Now I recently started playing Borderlands 3, and after some 10 hours of playing, it just shut down on me. Somewhere around 2 hours into the game I updated my GPU drivers, because I was experiencing issues with framedrops, but other than that I did not change anything on my PC. I thought it was just one of those weekly tantrums my PC throws, but upon restarting the PC and the game it shut down again within less than an hour. After some more attempts and shutdowns, it didn’t even want to show me the title screen. It just shut down as soon as the introductory ‘credits’ had played. I also started receiving random shutdowns way more frequently without running any games or heavy programs. Sometimes after only 15 minutes of running. There were several issues with my PC that I was aware of, and several issues that occurred in the past I had resolved:
  • My Windows refused to update since 2017. I know, stupid, but I couldn’t fix it, and I didn’t experience any software issues because of it. I was running on v.1607 and no later update would install, not via the installer, not via an ISO, not in any way. Register repairs and such didn’t do anything, so I had to do an in-place repair with an ISO of the exact same version (1607). This was succesful, and after this repair, I was able to finally update to the most recent version of Windows. The issue remained. I also did a clean install of my drivers and the game, but nothing helped.
  • I checked the inside of my PC. There was a lot of dust, so I cleaned it up a bit. Didn’t work. I bought an aerosal spray from a IT hardware store designed to clean electronics, and removed even more dust from the CPU fans, mainboard, case fans, GPU chips and fans, vents and the inside of my PSU. After cleaning the PSU, I was able to start Borderlands 3 and play for an hour again, but after this the system shut down again, and starting the game was again impossible. I tried other games, and the same thing happened. Even when I enabled shaders in Minecraft, my PC just shut down without even attempting to display a single frame.
  • In the past, I had a similar issue where my PC would shut down during Skyrim after ~ 2 minutes. Simply blowing off some dust from the GPU resolved this completely and no major issues persisted for half a year.
What I already tried to fix the problem:
  • I reinstalled Windows using an ISO, and updated to the latest build.
  • I updated my video drivers and did a clean install.
  • I removed dust using aerosol spray from all components I could reach.
  • I removed and reconnected the RAM. No issues.
  • I ran a full memory diagnostic through Windows. No issues.
  • I monitored the temperatures of my hardware and the movements of the fans. Nothing is overheating, all fans are turning and seemingly dealing with the loads just fine.
  • I monitered the load of my hardware. Neither my CPU, GPU or RAM is working over its capacity. The shutdowns sometimes occur when the system is virtually idle (never fully idle!)
  • I ran dxdiag. No issues found.
  • Checked all my drivers. No issues found.
  • Reset my overclocking settings in the BIOS, issue persists.
  • Thoroughly checked all the connections within my PC. Nothing seems loose or out of place. I even traced all cables and wires to their sources using the manual. Nothing seems off.
  • Ran HWiNFO64 and logged the data in a .csv file until the pc shut down. Not only did it not finish the log, it also showed nothing of interest that pointed to too high voltage, overloaded components, high temps, alarming readings from sensors, etc.
  • Event logs. Nothing. They are absolutely empty after each shutdown. It only tells me the system shut down unexpectedly when it is rebooting already. Within several minutes before the shutdown I usually don’t even see warnings.
  • Enabled memdumps. They are not created. After a shutdown there is no dump to be found anywhere.
  • New power cable.
  • Other electricity socket.
  • Remove hardware such as webcams etc. Nothing made a difference.
  • Disabled programs I use a lot. None made a difference.
  • Virus scans. Many.
  • Ccleaner registry clean-up.
  • Scan for hardware changes.
  • Google.
  • I did not update BIOS yet, because I am very afraid my power is cut during the updating, rendering my entire motherboard useless.
  • I did not try another PSU, because I don't have any. My wiring is also very rigidly attached to the case by the assembler, so I want to be quite sure that the PSU is the problem before replacing it.
My specs and devices:
  • CPU: Intel Core i7-4790K, not overclocked
  • GPU: MSI GTX 970 Gaming (MS-V316) 4GB
  • RAM: Corsair Vengenace Pro DDR3 16GB (2 x 8GB), 1866MHz CMY16GX3M2A1866C9
  • Motherboard: ASUS MAXIMUS VII HERO Intel Z97 chipset
  • Seasonic G Series SSR-650RM (80+ GOLD) 650W
  • SSD 1: Samsung 840 EVO 250GB
  • HDD 1: ST1000DM003 - 1 TB
  • HDD 2: ST3000DM001 - 3 TB, 2TB usable.
  • CPU cooler: H80iGT Corsair water cooler
  • Optical Drive: ASUS DRW-24F1ST
  • Wi-Fi: Broadcom BCM4360 802.11ac WNA
  • Keyboard: Steelseries Apex
  • Mouse 1: Logitech G502 Proteus Core
  • Mouse 2: Logitech G300
  • Headset: HyperX Cloud II (USB)
  • Monitor 1: AOC G2460V (HDMI - GPU)
  • Monitor 2: AOC G2460V (Display Port - GPU)
  • Monitor 3: LG 22EN43 (VGA - Motherboard, Intel HD Graphics 4600)
  • OS: Microsoft Windows 10 Pro, Version 10.0.18362 Build 18362 64-bit
  • BIOS Version/Date American Megatrends Inc. 2702, 27-Apr-15
  • SMBIOS Version 2.8
Sep 24, 2019
and the make and model of the psu? how old it is?
The full details I found on the original box:

Seasonic G-Series
SSR-650RM Active PFC F3
80 PLUS Gold / Energy Star / ErP Lot 6 2013 Compliant
Protection features: OPP/OVP/UVP/SCP/OCP/OTP

Total output 650W

Bought it new from the store in 2015.