Short answer: a PC that switches off under heavy load is often an undersized or failing power supply, but overheating is just as common. Check temperatures and wattage first, then cables, then try another power supply.
Power off or crash?
The way it shuts down is your first clue.
| What happens | Most likely cause |
|---|---|
| Screen goes black and the PC is instantly off, like pulling the plug | Power supply protection tripping, or overheating protection |
| Blue screen or error message, then restart | Drivers, memory, an unstable overclock or software |
| Game freezes or crashes to desktop, PC stays on | Game or driver problem, rarely the power supply |
Work through these in order
- Check temperatures. Use a monitoring tool to watch processor and graphics card temperatures while gaming. If they shoot up just before the shutdown, look at cooling and dust first.
- Check your wattage. Compare your power supply with your card in the wattage guide. Undersized units are the most common power cause, especially after a graphics card upgrade.
- Reseat cables. Switch off and unplug, then firmly reseat the 24-pin, processor and graphics card cables. Check the 16-pin plug for discolouring.
- Remove overclocks. Reset any processor, memory or graphics card overclock to stock.
- Check Windows. Look for Kernel-Power Event ID 41 in Event Viewer. Microsoft says a BugcheckCode of zero might point to a power supply problem.
- Try another power supply. If you can borrow a suitable unit, a swap is the surest test.
Why the power supply cuts out
Modern graphics cards draw short spikes of power well above their rating. A power supply that’s too small, too old or not built for these spikes can see them as a fault and switch off to protect itself. See transient power spikes explained.
A power supply that’s getting worse with age can trip at loads it used to handle. If yours is past its warranty, that’s worth considering. More in signs your power supply is failing.
Quick fixes while you decide
- Cap your frame rate in game settings. It lowers the graphics card’s load and its spikes.
- Use a separate cable for each graphics card power socket.
- Plug the PC straight into the wall to rule out a faulty extension lead.
These can hide the problem, so treat them as a test, not a cure.
If you need a new one
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Questions
Why does my PC turn off when gaming but not browsing?
Gaming loads the graphics card heavily, which raises power draw and heat. Either can trigger a shutdown.
Can a power supply be too small and still work most of the time?
Yes. It can run fine at light loads and only trip during heavy gaming.
Will a bigger power supply fix random shutdowns?
If the cause is an undersized or worn unit, yes. If it’s overheating, no.
Can a bad cable cause shutdowns?
Yes. A loose graphics card or processor cable can cut power under load.
What does Kernel-Power Event ID 41 mean?
Windows restarted without shutting down cleanly. A BugcheckCode of zero can point to a power problem.
Sources
- Microsoft: advanced troubleshooting for Event ID 41
- MSI: best PSU for AMD RX 9070 XT
- Tom's Hardware: why power connectors are melting, and what to do (June 2025)
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