I'm Jon Gerow and I'm head of the R&D department that makes the power supplies at CORSAIR. I have a great team working with me to make sure we construct our power supplies as reliable as possible, while still keeping within our customers' budget. I have been made aware of a "clicking" noise coming from our 2025 RM1000e in some customers' builds. And I just wanted to write an open letter to explain that we understand your concerns, are aware of the issue and are here to help.
First off, EE 101: LLC Resonant Mode is a platform we use in most of our power supplies to ensure excellent efficiency across a wide range of loads versus other PWM controlled platforms. The RMe series of power supplies use this technology.
The name comes from the parts used in the circuit: Two inductors (L) and a capacitor (C). We can easily get into the weeds about how this technology works on another day.... or just ask ChatGPT! But, for today's tech note, we're going to focus on how the resonance of the parts react to the load. In the early days of using LLC in consumer products, we would use an easier to digest term like "Frequency Conversion" to explain how this works in layman terms.
Essentially, as the load changes, the frequency is modulated between the switching MOSFETs. The switching occurs at near zero voltage, which gives us the term "Zero Voltage Switching", or ZVS. This is how we increase efficiency. By reducing the amount of loss between the MOSFETs.
What Causes the Clicking Sound?
So, when the MOSFETs switch, the energy produced is stored in a component called a "resonant tank” and is output through a high-frequency transformer. The noise you're hearing is the frequency of the power going into the tank, not out.
At certain loads, the frequency of the energy going into the resonant tank is right at the start of your ear's ability to hear high frequencies. While the noise is always there and is more like a waveform with varying degrees of frequency, we're only hearing the sound when it dips down into human hearing frequency, so it sounds more like pops or clicks.
Is the Noise Harming my PSU?
Fortunately, this should be a point that instills comfort in the user. None of this "noise" is making its way to the DC output and it can't inflict any damage to your computer's components.
Reproducing this noise has been challenging because the load on the PSU must be within a particular range. Using different motherboards, CPUs, GPUs, and benchmark or burn-in programs would yield results in one combination versus another. Adding to the difficulty is effect of thermal drift on resistors. As the PSU heats up, some of the resistors, like the shunt resistors that are used to measure load and control the switching frequency, would cause relatively static loads that allowed us to reproduce the sound to eventually go away. Once the load was removed, the noise would return as the unit cooled down.
I love getting into the troubleshooting part of my job and it does make my job fun. But at the end of the day, we know what our customers want is a quiet PSU. The good news is we've isolated the noise, know where the noise is coming from, and with the change of just a couple resistors, can prevent the noise by limiting the frequencies generated to outside of human hearing. No guarantees that your dog won't still hear something, though.
This said, it will still take time to reconfigure these power supplies, assemble them and ship them. So, in the meantime, we encourage users to continue using the product with the peace of mind of knowing that this is only a noise and not anything nefariously worse and we will be more than happy to exchange out the PSU with a quieter version of it, once they are available.