I run a small computer repair shop and, over roughly five years, I've encountered three Corsair RM850 power supplies that failed a PSU tester. In one recent case, the failure was accompanied by a dead Asus B450M Plus motherboard. The DDR4 memory, GTX 1060 Ti, and Ryzen 7 5800X appeared to survive, and I was able to move them into a B550 system.
The other two failures were more serious and also damaged additional components. These systems belonged to different customers, so they weren't all built or used in the same environment by me. What could cause a supposedly high-end power supply to fail catastrophically and take other hardware with it? Is this likely to be defective units, power-quality problems, installation issues, or simply bad luck? Interestingly, inexpensive basic power supplies often just stop working without damaging anything, while some budget 850W Bronze units I've used in gaming builds have been reliable so far.
4 Answers
A premium label doesn’t guarantee that a unit can never fail. The protection circuitry is supposed to shut the PSU down safely, but a component can fail in a way that allows an overvoltage or transient onto the motherboard. A basic PSU tester usually checks only a few rail voltages and the power-good signal, so it can identify a dead unit but won’t necessarily explain what failed or prove that it damaged the other hardware.
I wouldn’t treat the cheaper units surviving as proof that they’re safer. Some low-cost supplies simply die with minimal output, while others have weak protections and can damage components. For replacements, use a model with independent reviews, verified over-voltage and over-current protection, and a solid warranty rather than choosing only by wattage, price, or the logo on the case.
Before condemning every RM850, document the failure conditions: test the outlet under load, inspect the mains wiring and surge protection, check for reused modular cables, and look for shorts or damaged connectors in the affected computers. If the systems came from unrelated locations and the same model still fails repeatedly, then a bad batch, revision-specific issue, or unusually unlucky sample becomes more plausible.
Repeated PSU failures across different machines make the incoming power and wiring worth investigating. Voltage spikes, poor grounding, a faulty surge protector or UPS, and unstable mains power can all stress a PSU over time. Ask whether the affected systems shared the same building, outlet, extension lead, or power strip before assuming the brand is solely responsible.
These were customer systems rather than machines I built, so they weren’t all used in the same setup. I’m mainly trying to understand whether the RM series has a reliability pattern or whether this is just an unlucky sample.
It’s also worth checking the PSU’s exact revision, age, cable compatibility, and installation history. Modular cables from another power supply can cause immediate damage even when the PSU itself is fine.