The Corsair RM850x (2018) PSU Review: Exceptional Electrical Performance

Conclusion

Corsair's engineers designed the RMx series to offer a great balance between quiet operation, high quality electrical performance, and reasonable pricing. In practice, the series is bridging the gap between the value and the top-tier performance products that Corsair produces. In that respect it serves as an upgrade over the relatively simple but highly reliable TXM series, offering quieter operation without the high price tag of an AXi series unit.

The primary marketing point of the RMx series is quiet operation and the RM850x did not fail to deliver. Its fan does not even start with loads lower than 200 Watts, meaning that the RM850x will operate fanless while any modern PC is idling or performing simple everyday tasks, like browsing or media playback. For most users, the fan of the RM850x will only start when a performance graphics card is put to use, i.e. while gaming.

Although the primary selling point of the RM850x is its quiet operation, we cannot help it but point out that the electrical performance of the particular platform is exceptional. The RM850x greatly surpassed our initial expectations and delivered astonishing power quality during our testing, with figures that we usually see on products retailing for twice the price. We have no complaints regarding the electrical efficiency of the platform either, as it easily surpassed the 80Plus Gold certification requirements regardless of the input AC voltage.

The Achille's heel of the RM850x is its thermal profile design, which favors quiet operation over low operating temperatures. This works perfectly well for most scenarios, as the vast majority of users would never fully load a 850 Watt PSU for extended periods of time. As such, the RM850x rewards its owner with excellent acoustical performance, generating no noise when lightly loaded and retaining comfortable noise levels even when the load is high. However, if the load is excessive and the ambient temperature is high, the efficiency of the RM850x will degrade slightly, as the active components will start becoming stressed. But the only real-world scenario that matches these requirements is cryptocurrency mining, for which the RM850x clearly is not the best choice.

Corsair currently sells the new version of the RM850x for $130. The price is admittedly a bit high for an 80Plus Gold certified PSU, yet it's more than reasonable when taking its performance and the lengthy 10-year warranty into account. And if anything, Corsair is probably creating internal competition against themselves, as the RM850x offers astonishing electrical performance for a significantly lower price than the company's respective HX and AX units. So if you don't mind dropping one efficiency certification level – and merely to 80Plus Gold at that – then the RMx series ends up being an extremely attractive power supply even for high-end users.