It's surprisingly hard to find decent reviews that feature bad fans alongside good ones, but even the spread between decent fans is pretty illustrative (from overclockers.com):Can you show me that?
I have some cheap 120x25mm thick ball bearing fans that are worse than anything on that chart in noise vs. performance and enough samples of them to know it's normal for them.
Regarding dBA vs. RPM (vortez.net):
There is damn good reason why fans like the Nidec Gentile Typhoon, Noctua NF-A12x25, and more recently, the Arctic P12, are well regarded...especially when they have to overcome restriction.
Sometimes it's loud and annoying.Isn't coil whine supposed to be quiet, but annoying noise?
Tonality is important. That's why bearing noise generally bothers me more than airflow noise, and high pitch noise is generally more annoying for most people than lower pitched noise.The big irony is that I'm deaf (moderately on one ear and severely with other), but computer noise bothers me a lot. For some reason it's really audible to me and I really can't stand it. Yet for some reason, certain stock coolers are soothing for my ears. I remember some old AMD cooler in university's computer. It was typical old 6000 rpm capable jet, but it didn't bother me. It was rather pleasant. But one day, when I plugged in that Yate Loon from PSU (which is essentially a server fan used in PSU), it was just plain obnoxious and unpleasant. It was so bad, that it was almost vacuum cleaner bad.
Unfortunately it's also pretty subjective and thus hard to review; one has to experience it. Subjectively speaking, the A12x25s are very tolerable--and slightly more pleasant than the Arctic P12s, for example, even though they have the same dBA.