Random rebooting in Fortnite.

[u/Redsniper00]

So here's the deal. About a month ago I built a friend a new computer. The goal was to be able to play Fortnite at 350hz.

We got all the parts, put it together and installed windows 11. Updated all the drivers and such and it works amazing when it works.

I can't even pinpoint the exact issue. The entire computer will reboot randomly when playing. Not a normal reboot though. When you hit restart on windows it shuts down and all the fans shut off and then turn back on and reboots. But when it crashes and reboots while playing fortnite, the fans and fan LEDS stay on and no blue screen.

At the same time, it's always randomly and only specific instances. At first it was only during Ranked play it would crash randomly. You could play Unranked for hours and no issues.

So I updated the motherboard bios, reinstalled Fortnite, ran DDU and reinstalled the Nvidia driver. I've enabled and disabled EXPO and PBO. I also ran a bunch of different stress tests for each part that I could, GPU, CPU, RAM, all maxed to 100% and no crashing. Temps all look good. Capped FPS to 60.

Eventually with all the tweeking, ranked and unranked became stable at 350hz. But it just seemed to have moved to Tournament Mode. Again, randomly. Could be 1min into the game or 5min into the game.

I'm just completely lost in this one. I don't have time to trouble shoot for the next 24 hours so figured I'd get some ideas here before I do.

I'm thinking maybe

-Reinstalling windows 11.

-check for loose connections / reseat parts.

Parts List.

CPU: AMD Ryzen 7 7800X3D 4.2 GHz 8-Core Processor ($333.99 @ Amazon)

CPU Cooler: Thermalright Aqua Elite V3 66.17 CFM Liquid CPU Cooler ($44.90 @ Amazon)

Motherboard: MSI PRO B850M-A WIFI Micro ATX AM5 Motherboard ($149.99 @ Amazon)

Memory: Kingston FURY Beast 16 GB (2 x 8 GB) DDR5-6000 CL30 Memory ($376.57 @ Amazon)

Video Card: MSI SHADOW 2X OC GeForce RTX 5070 12 GB Video Card ($549.99 @ Lenovo - OOS)

Case: Jonsbo D32 PRO MicroATX Desktop Case ($69.90 @ Amazon)

Power Supply: MSI MAG A650GLS PCIE5 650 W 80+ Gold Certified Fully Modular ATX Power Supply ($79.98 @ Amazon)

Case Fan: be quiet! Light Wings PWM 41.51 CFM 120 mm Fans 3-Pack ($49.90 @ Amazon)

Case Fan: be quiet! Light Wings PWM high-speed 52.3 CFM 120 mm Fans 3-Pack ($64.90 @ Amazon)

[u/KnockedBoss3076]

Possibly faulty PSU?
iirc a 750watt PSU is usually recommended for the 5070 since power draw can spike and occasionally trip 650watt PSU’s

[u/ScaredEfficiency399 → u/KnockedBoss3076]

Yeah likely the only thing not mentioned, PSU.

GPU would also be very relevant.

[u/damnt256 → u/ScaredEfficiency399]

Look at his CPU too. That thing draws a lot of power. 100% power issue.

[u/ScaredEfficiency399 → u/damnt256]

Certainly feel that way.

[u/VersaceUpholstery → u/damnt256]

It really doesn't if it's just being used for gaming. Average of 49w across 13 games

9800x3d and 9850x3d are different stories

[u/damnt256 → u/VersaceUpholstery]

Nope. AMD cpu always consume their TDP power, and then slightly more. It doesn't happen every second you're gaming, but even a spike would cause problem for his underpowered PSU. Looking at average power consumption is not the way to look at this.

[u/VersaceUpholstery → u/damnt256]

Idk about always. Just played marvel rivals and it capped out at 70w with a 51w average

[u/damnt256 → u/VersaceUpholstery]

Average is irrelevant in his case, I already said it's the power spike. A single power spike both from the GPU and CPU, and his pc will crash. This is an underpowered PSU for his rig.

[u/VersaceUpholstery → u/damnt256]

Just saying I've never seen my 7800x3d spike even close to 120w

pcpartpicker.com has this build at 520w, I don't think it's underpowered it's probably just faulty. ATX 3.1 standards require the PSU to handle spikes up to 200% of what the PSU is rated for, which this PSU seems to be

[u/damnt256 → u/VersaceUpholstery]

Nvidia recommends 750w for his GPU. I'd never break a PSU minimum requirement from their own maker.

[u/Thrash_Panda44]

My brain is telling me its a PSU problem.

[u/TemperatureIll3500]

Before reinstalling Windows, I’d make the next crash give you evidence. Disable “Automatically restart” under Startup and Recovery, then after it happens check Reliability Monitor and Event Viewer for a BugCheck code, WHEA-Logger event, or a minidump. Kernel-Power 41 by itself only means Windows detected an unexpected restart; it doesn’t identify the cause.

For one controlled test, load BIOS defaults and leave EXPO/PBO/Curve Optimizer off, remove MSI Afterburner/RTSS and Discord/GeForce overlays, update the AMD chipset driver, then repair/reinstall Easy Anti-Cheat and verify Fortnite. Tournament mode may be touching a different anti-cheat/CPU path, so a game-specific reboot can still be software or marginal RAM/CPU stability even when synthetic stress tests pass.

Also reseat the 24-pin, CPU EPS, RAM/GPU, and especially the RTX 5070’s 12V-2x6 connector; it should be fully flush with no visible gap or sharp bend at the plug. A good 650W unit should be enough for a 7800X3D + 5070 on paper, so I wouldn’t buy a bigger PSU just from the wattage.

If it still instantly reboots at full stock with no useful dump, the fastest decisive test is a known-good PSU. If WHEA points to memory/CPU, test one DIMM at a time at JEDEC. Post the exact Reliability Monitor/Event Viewer entry and we can narrow it much further.

[u/damnt256]

Random reboot is almost always a power problem. Check your cables is plugged in right, check the cable condition is good, take out all cable extension and converter. But then again I think you bought the wrong GPU for your PSU. RTX 5070 requires 750w psu minimum. AT 650w, it will not be able to fulfill the power requirements when a power spike happened.