anway, I'm now running the fans at 7V (5V just raises the temps too much for me), the CPU fan is akasa amber 92mm @800rpm on idle, the PS fan is also 7V and around 800rpm.
But now that the case is nice and quiet, I'm hearing this regular, rhythmic hum. Its volume goes up and down in a regular sine wave. The noise doesn't sound mechanical, like a disk or fan whirring, but like an echo of another sound. I turned things off to isolate the noise and I don't think it's coming from any particular component, but the case itself. I think the case is resonating. It's not a pleasant sound.
The spcr reviewer also hears a humming when running fans at 5V but not at 12V. Problem is I hear it now even when fans are running at 12V. I don't know if I did something to introduce this noise, or it was always there but now I'm tuned to it.
If someone had the same experience with this case please let me know how you dealt with it. For that matter, all other suggestions are welcomed
