My PC completely loses power after roughly one to two hours of gaming. There is no blue screen, error message, or normal shutdown—everything just turns off. I recently replaced the motherboard, CPU, and power supply, and I used the cables supplied with the new PSU. I've also tested the RAM both at its default 4800 setting and with XMP enabled. The CPU cooler is a Peerless Assassin 120. Before taking the system to a repair shop, I'd like to know whether this sounds more like overheating, a power-supply problem, or something else, and what checks I should run.
3 Answers
A complete power loss without a blue screen can also point to the PSU, especially when it happens only under gaming load. Check the PSU’s rated wattage and the GPU power connections, and avoid using modular cables from another power supply. If possible, test with a known-good PSU or use a multimeter or monitoring tool to check whether the rails become unstable under load. RAM testing makes memory less likely, but it doesn’t rule out every power or motherboard issue.
Kernel-Power 41 is expected after an unexpected loss of power; it records the symptom rather than identifying the cause. Event Viewer usually won’t prove that overheating caused the shutdown. Check temperatures and fan speeds first, then test the PSU and motherboard connections. Also try temporarily disabling XMP and running the system at default settings to see whether the crashes stop.
The first thing I’d check is CPU temperature and cooler installation. Remove the cooler, confirm any protective film has been removed, clean and reapply thermal paste, make sure the heatsink is making even contact, and verify that its fans are connected to the correct motherboard headers. Monitor CPU and GPU temperatures while gaming with a tool such as HWiNFO. Don’t overtighten the cooler, and follow the mounting instructions carefully.

Thanks, I’ll reinstall the cooler and monitor the temperatures under load.