Question PC rebooting under load

May 18, 2021
Hey, in the last months i´ve been having a problem that couldn´t solve at the moment. My PC reboots in some load cases. I'll include all the information I've got about the issue and i would like you to carefully read all the post, thanks in advance.

I don´t play a big games catalog, and it has happened to me in certain cases and loads I'll describe below. Reboots are like when power goes out for a sec, it turns off totally without any software indication or crash, all leds and fans stop working and about 3 seconds later PC starts running again.

Let's start with Fallout 4, i downloaded this game and after playing some hours i got a reboot, didn't got another one until some days later, but it wasn't a major problem there, this was the first game in which I detected the error in first days of march, previously I wasn't playing heavy games because I was just starting in the world of PC gaming. Some days later, i was getting some moments of low FPS and I decided to deactivate the game VSync applied by default, this isn't an option in the game because it doesn't have actually a video settings menu, so i had to change VSync to 0 in the game documents. From there my GPU would be in 100% all the time, and it is one of the more power eating games, it uses about 105-110W of my GPU while most games use amounts in the range of 80s and 90s, and well, VSync off pulled my PC to a reboot every single time about 3 to 10 minutes in the game. I got realized that a small undervolt of about 50 mV (without underclock) eliminate this problem by complete, and haven't had a single reboot since there, this makes me think totally about PSU or maybe power strip (?) problem.

About Fortnite, first time I played it I got the issue after about 30 minutes playing, as i liked the game i was forced to live with the problem, it occured normally in the first game but sometimes would not happen in a game session. Using a undervolt and an specific GPU connector i feel it helped a bit, but problem was still happening. After some weeks, problem started happening always in the lobby or in the first minutes of play, even with major undervolts and underclocks. I decided to put a lower FPS limit and reduce graphics to medium, which would drop GPU usage to levels like 50%, can't remember exactly, that allows me to play without problems. One thing i have to say is that restarts happened in several times in the load screen: when exiting a match to the lobby or searching another one, GPU usage goes down in this screen, so maybe this is for a change in the computer load.

About stress tests, OCCT its a solid but weird example. With error detection on, test won't run and stop automatically 3 seconds after I press the start. With error detection off, GPU and PSU tests will instantly reboot my system, as if the test start button was an option to the shutdown one. I've seen this is normally indicative of a PSU problem.

AIDA64 gives me mixed results, it can reboot my PC in less than 15 minutes or just don´t do it. When the reboots doesn't occur, it is like a "good PC boot" and i can run it a lot of times and hours without restarting.
I've tested FurMark and Heaven Benchmark, they don't reboot my PC.

Returning to the games, I'll now talk about those games which aren't actually demanding but make the problem happen.

Euro Truck Simulator 2 started giving me restarts when i raised the settings a bit, including turning VSync off, this game gives transient loads to my computer, even with VSync off, GPU usage goes from levels like 30 or 50% to the 80-90% and sometimes arriving 100% when looking inside the cab (it's like looking to sky in other games ig). Restarts in this game are random, can occur after some minutes but more likely after playing for about an hour or more. I can prevent the problem dropping settings a bit as i said. I also got a restart once when finished a delivery and reward menu popped.

Cities:Skylines, i played the game for months in low settings because my main objective was to concentrate in the game (city building), one day I decided to raise the settings to medium, it gave me a reboot about 10 minutes later. As a massive city builder, game is programmed for processing high amounts of entities before high performance, so it doesn't give more than 40 FPS and doesn't use much resources more than RAM, when zooming out GPU usage can reach higher levels, like 80-90%s.

Battlefield V, i played some hours and got a restart when entered cinematic scene, i guess that modified the resources usage and maybe transient load made some protection jump?

Aim Lab, not a demanding game for training aim, made my PC restart once when i changed to Google Chrome for changing music, i guess it applied a different kind of load again, didn't alt + tab, just change trough home button + select chrome. Universe Sandbox², played it very short time, around 30 minutes the day I installed it, day after it, i got a restart while playing, it was a scenario with a certain load (fragment collision), it's also not a game forcing full GPU usage.

Now I should highlight that there are several games that aren't causing this issue in absolute, it's probably around the other half of my game catalog, but i can Resident Evil 3 and Forza Motorsport 7, I've played a very short time in those games but had no problem with them in that period, they pull 100% GPU usage. also pull almost all of the graphic resources and won't crash my system.

my specs:
CPU: Intel Core i5 9400
MOBO: Gigabyte H310M M.2 2.0 (4 pin)
RAM: Mushkin MES4U266KF8G 2667 MHz CL19
OS Drive: WD Green 240 GB SATA SSD
Storage drive: Seagate Barracuda 1 TB SATA HDD 3.5" 7200 RPM
OS: Windows 10 Pro 20H2 and last recommended updates
CPU cooler: Intel stock fan
PSU: Thermaltake Smart 600W 80 Plus (white) SPD-0600P

Parts are between 7 and 8 months old

Apart from the undervolt and mentioned things, I've carried out every software solution you can see in internet, like power options, remove overclocks, make scannows, etcetera, reseated connectors, GPU and RAMs, did memtest and cleaned PC, not with compressed air but with a brush. After exhaustive investigations, I decided to send GPU and PSU to warranty where I bought them since I bought them in the same place, they said they couldn't find any problem in them so I'm very frustrated for this, they said they tested them with a system similar in specs to which I described. I don't know if power supply should be the issue, it is my main suspicion but they say they couldn't find anything and that makes me lose hope, I also think it could be a thing in the VRMs, my Mobo isn't exclusively designed for gaming and its 4 pin, and transient load thing also makes me think about it.

I live in Argentina so my possibilities are a bit limited, a Tier C PSU is the maximum i could buy but i should have to be sure for it, my budget for changing parts right now is practically zero, so please understand that.

I would appreciate any kind of idea or suggestion, i promise to answer as soon as I can and try anything for fixing this.
I ever experienced trouble like this after long reading, i quickly diagnose that my new psu (a CX 550 new) is having sort of faulty, stressed FPU alone, Furmark alone, FPU + Furmark, it shuts the pc off and reboot itself. but when i grab my Ol' VS450, used the test method i mentioned before, leave it at an hour each, no reboots.

So it might be psu as the culprit here. try using your friend's PSU or other spare PSU.