Hi, sorry for the necro, but I have the same issue with new corsair rm850i unit. It’s insanely bad and as the person above described - even a slight mouse movement will bring low pitch noice and stressing the CPU is making it worse. It seems CPU related and in games it’s not that loud (but still there). For the price of the PSU and corsair reputation this is insulting. Tested for sure it’s the PSU, returning my old corsair TX950 fixed the issue (and that PSU also for a coil whine issue, but not nearly as bad). I will return it in the next few days and take another one, serious question - should I go for another rm850i or another brand as from two power supplies from corsair both are having bad coil whine and via my job (network/system administrator) a lot of machines was in-front of me - never saw that bad coil whine in my life. It’s basically constant and getting worse with any CPU load, only full idle is kinda quiet most of the time and machine off. It's also different high pitch noise, for example in cinebench, prime95 small fft, smallest fft, blend - but all insanely loud and distracting. Like something is piercing through my ears. Opening chrome brings the sound, windows booting, mouse movement (but it's quieter in those with windows booting noisier because of the higher CPU load). Tried to mess with VRM's settings for the board, tried to turn off C state (there is global option for that), tried to plug in the second 4 pin CPU power on the board, tried also two PCI-E cables for the 5700XT and tried single rail instead of multi - nothing changed.
My other specs: asus corsair x570 hero wifi, 3600x, Kingston 2x16 @3600 cl16, 5700xt, ssd’s +hdd’s combo.
Seriously, I know it’s corsair forum and all, but are all of their PSU having issues with coil whine and why it’s not mentioned in reviews (including yours)? I actually buy that PSU based on your review instead of be quiet 850w platinum that was scored lower from you and is more expensive. I was sure that the tx950 issue will not repeat and indeed, it’s x10 worse.
Sorry if I sound angry, but it’s frustrating to happen second time on super positively reviewed PSU’s that are anything but cheap. I know how it depends on hardware and whatnot, but common. :(
So it’s basically stranger asking you for a favour and advice how should I proceed? Risk with another rm850i or change the brand? In my country it’s not that trouble free to return parts, sadly. So I am really worried that the one they give me will have the same issue.
Sorry for the long post and I will be really thankful for advise.