Personally I have no argument that air is easier to do quieter. I know this because I've got a noisy MCP350 that I just can't shut-up in my watercooling setup, despite suspension mounting (if hanging by the tubes actually counts as a 'mount'). The WD5000KS runs a close second for noise - but that's not irritating like the pump whine.

That said...

I couldn't O/C on air like I do on water. I know I could do an basically inaudible system with air at stock speeds - but when you're running 3.2-3.6G from an E6600, and 800Mhz+ core from a 9800GTX, it's just NOT POSSIBLE to quietly cool that with air cooling, IMO. If someone has done it, please tell me how.

I still believe WC is the best alternative for overclockers who like (relatively) quiet PCs. Silent is quite hard (simply because pumps are difficult to work with), but is also plausible on a heavily overclocked system. The same cannot be said for air, and in fact the best air rigs still seem to rely on undervolting CPUs.

FWIW, Mojo was talking about Slip Stream 800 @ 7v, that's 540rpm.

I also feel that your quote from MikeC is quoted out of context. That fan was used as a front intake fan, which means it's going to be more audible then cpu fan or rear case fan at similar rpm.

P.S Imo front intake fans are useless, if you are using rear fans.

Not if you've got 10-12 drives in your system like Wibla and I do... example: The Monster.

I tried running my setup (I've got 10 drives total) without any front intake fans, and my hard drive temperatures quickly rose up to the mid 40's. Compare that to the 30-33C temps I get with undervolted fans in front and you'll see why front fans aren't useless. (My system has two rear 120's as well as the 120 from my Corsair HX620)

Well imo they are still useless. There's nothing wrong with mid 40's.

Mid 40's at idle meant mid 50's at load. That's pushing the manufacturer's maximum temperature ratings, so your statement about them being "useless" isn't always true. In a single or dual hard drive setup, you can usually get away without front fans, but not always.

I believe my reply was fair & appropriate. Doesn't it provide a good counter-example to Mojo's conclusion?

In the Mini review, SPCR found that a ~19dBA fan (Slipstream @ ~800rpm) was too loud while running in a ~23dBA system in a 19dBA environment. Reducing the fan's noise by 1-2dBA dropped its noise level below another component's, giving a significant improvement in overall noise. But SPCR still managed to measure a .5dBA increase in the system's sound output when the fan was turned on at the slower speed.

So the fan was more audible in actual system use than when running in "fan testing" mode. More importantly, the fan contributed significant noise while theoretically running below the ambient noise floor. The conclusions to reach are that implementation counts & that you cannot judge an entire system solely by its components.

I think your mistake is to rely just on the numbers. That's why SPCR supplies audio recordings of the fans they test.

A lot depends on the character of the noise. As I have already said, and as many others have found, I do not need to run my fans at 5V for them to be inaudible. I can't hear them at 7-8V, even 9-10V in a P182 with some Yate Loons. I had my hearing tested recently and it's above average for a 28 year old. I live in a fairly quiet house.

This is the point you seem to be missing: it doesn't matter what differences you can measure in a soundproof room with sensitive equipment. What matters is that I can't hear it in my bedroom when sat in front of my PC. If I can't hear the fan at 7V, there is no point running it at 5V or any lower because it will make no audible difference to me but will be pushing less air.

I'm not sure how else I can state this argument to make it any clearer. In fact, you yourself seem to be supporting my argument with the statement "The conclusions to reach are that implementation counts & that you cannot judge an entire system solely by its components." The only difference is you seem to have come to a somewhat illogical conclusion for some reason.

Sorry, I am confused. You agree with my explicit conclusions, but what is the "illogical conclusion"?

You seem to be saying that running your fans at 3V instead of 5V or 7V makes an audible difference. On the other hand you say you cannot judge a system simply by it's components, implementation is important as well.

That is the basis of my argument. Yes, you can measure less sound coming from a fan running at 3V in a lab, but in a real system in a real office/bedroom, you can't hear a 7V fan inside a P182 so there is no point running it any lower than 7V.

If you can't understand now, I give up.