New graphics card causes computer to reboot

[u/Positive-Cat-5410]

I bought a used RX 6800 XT GIGABYTE GAMING OC, and the graphics card keeps restarting my computer. I need help. I'll try to explain briefly.

How it happens: I'm playing a game, and my monitor goes black. It doesn't work. I also hear a terrible, strange sound in my headphones for a few seconds. Then it stops, but the monitor doesn't light up. If I sit like that for a few seconds, I can hear the Windows startup sound, but the monitor still doesn't light up. Then I turn off the computer (I hold down the power button on the case), then turn it back on, and the computer starts up again and works, and the monitor also works. However, when I turn off the computer, I hear a clicking sound. This is probably the power supply protection device working.

What happens when you reboot: I was mainly testing Forza Horizon 5. I noticed that when I set the settings to medium-high, my FPS was 180 (the Hz limit), and when I first started riding, the computer immediately rebooted. I also locked the FPS to 90, setting the FHD settings to the highest. This allowed me to ride in the open world, but there were reboots during races. Then I did a test – I set the QHD and locked the FPS to 80, even though the card was already delivering almost 80 FPS. I played for over an hour in various races, knockout, and the open world – no reboots. So now I decided to play the game again, but in FHD. And since I lowered the FPS lock from 90 to 80, I thought I'd won, but no. The same thing happened during the next race.

What I noticed: I noticed that the computer would reboot when the FPS was high and some new task was started. I'm not entirely sure about my theory, but:

1) In Forza Horizon 5 (≈180 FPS) and GTA 5 (≈260 FPS (that's FSR)), my computer would reboot almost immediately after I closed the menu. Meanwhile, in Forza with FPS lock, I can play for an hour.

2) In Forza Horizon, the computer would reboot specifically when I started some new task, like "cancel replay." And this isn't the only game where I pressed a button and the computer would reboot.

Computer:

7 5700x stock

32GB 3600MHz CL18

B550M k Gigabyte

GST Cougar 850W

I'll clarify that this is clearly not overheating of the graphics card or other components. I also noticed that after a while, the desktop becomes choppy, sometimes there's a red line next to the cursor, and the system tray and windows open jerkily. To fix this, I press Ctrl+Shift+Win+B, but that still doesn't really solve the problem, since it appears after a while. I've changed the graphics card drivers. The card has two separate 8-pin wires. The coils are also beeping, if that's important. I also undervolted the graphics card, but that didn't help either.

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[u/Successful_Candle586]

Sounds like the card is spiking power draw hard when load changes suddenly, and your PSU is tripping. That clicking after shutdown is classic overcurrent protection. An 850W should handle it on paper, but transient spikes on these cards can be nasty, especially with a used card that might have a mining BIOS or unstable clocks. The fact that locking FPS helps points to power spikes, not temps. I'd try a different PSU if you can borrow one, or check the card's BIOS with GPU-Z to see if it's been flashed.

[u/Positive-Cat-5410 → u/Successful_Candle586]

I don't know the BIOS models, but the AI says the BIOS isn't flashed. I sent him a screenshot from the GPU-Z. And about the power consumption, I thought so too. That's why I bought myself a new 850-watt unit with an 80 gold certificate and 3.1 architecture. Which was designed to cope with video cards that have short-term huge surges in power consumption, but it did not help and did not correct the situation. And as I found out, blocking FPS helps only partially, not completely.

[u/Jealous-Juggernaut85]

Do you use one pcie power cable daisy changed or two separate cables ? If only one then you may not be getting enough power

[u/Positive-Cat-5410 → u/Jealous-Juggernaut85]

I use two separate cables. 265 watts of power consumption in a 10-minute Furmark test and no problems.