I've got three fans in my case, an Xilence Red Wing 120mm rear exhaust http://www.xilence.net/en/products/fans ... g-120.html
, the fan that came on the Xigmatek HDT-D1284 top-down cooler (PWM) and a Arctic F12 PWM front intake.
The Xilence Red Wing is fine (I'm using a Zalman 100R resistor to run it at around 950RPM), the Xigmatek fan is not too bad but does have an annoying buzzing although it's probably not noticeable with the side on the case and a couple of feet away (it also won't run any slower than 992RPM with the Asrock BIOS set to Level1, which is the lowest it goes) but the Arctic F12 is very whooshy, even with a Zalman 56R resistor on it bringing it down to under 850RPM.
EDIT: I just realised I'd gotten confused and the Chassis (front) fan connector does actually have speed/temp control in the BIOS, it's the Power (rear) fan that doesn't. With the Artic F12 set to Level 2, it runs at 550RPM and is inaudible, so that's cool.
I've also got a Arctic F12 on my other PC's TRUE Rev.c heatsink and I haven't been particularly impressed with the noise from that either. I'm currently running it at 1265RPM because even with the TRUE my CPU gets too hot (55c) if I run it at low speeds and I haven't found a way to make it run slow at idle but full speed when needed (the BIOS can control it but if I set it to run slow at idle, it only goes to 900-1000RPM at full load). So at very low speeds it seems to be nice and quiet but at higher speeds seems a lot worse than some other fans.
I still wish I could reduce the speed of the Xigmatek fan a bit and the Xilence would probably be completely inaudible if it could run a bit slower as well but the Xigmatek's definitely the loudest at the moment.
EDIT2: Actually, I think the Xilence is a bit louder than the Xigmatek. The latter just got my attention due to the buzzing. It's weird now but sometimes it makes a raspy sound like it's catching on the heatsink but I don't think it is. If I lightly (and I mean very lightly, not pushing at all) touch the fan frame on the bottom then it seems to set this raspy noise off and then it stops when I remove my finger.
Now I've got the HDDs connected it's somewhat moot anyway as the whole case is vibrating but I ought to sort out the CPU fan, 'cos knowing my luck it will fail or start making some horrific noises the day after I send this PC to my brother for his birthday!
EDIT3: For the Xilence exhaust fan, perhaps I could take one of my Zalman RC56 cables (I seem to have acquired about six of them) and cut the resistor out and replace it with a higher resistance one. I'm not sure what resistance it would need to be though, as the 100R only gets it down to about 950RPM and I guess it needs to be at most 800RPM or maybe even around 550-600RPM like the front fan to be silent?