Looking for the right fan

dandragonrage · Post by **dandragonrage** » Sat May 28, 2005 4:38 pm

I need an 80mm fan for a UPS. The stock NMB fans (2 of them) push just under 40CFM and are rated 37-38dB. This is way too loud for me. I'm looking for something that's variable RPM that will push up to 40CFM when it gets really hot. Maybe 20CFM or so when it's not hot. Noise: as quiet as I can get it.

I am competent in electronics and don't mind using a separate thermistor if I must, but I prefer not to have to.

suggestions?

ckolivas · Post by **ckolivas** » Sat May 28, 2005 5:29 pm

Welcome to SPCR!
Have you read the recommended page?
http://www.silentpcreview.com/article63-page1.html

dandragonrage · Post by **dandragonrage** » Sun May 29, 2005 1:10 am

Thanks.

I did read it, but I noticed a distinct lack of any variable RPM fans that have CFM near what I want.

ckolivas · Post by **ckolivas** » Sun May 29, 2005 1:16 am

When you say variable RPM do you mean thermally controlled or something you could control yourself? Chances are your current fan with a Zalman fanmate2 would fulfil the second criterion since the flow is (apparently) what you seek for maximum.

dandragonrage · Post by **dandragonrage** » Sun May 29, 2005 1:29 am

thermally controlled, hence my using the word thermistor.

ckolivas · Post by **ckolivas** » Sun May 29, 2005 1:47 am

There are very few quiet fans that also have thermal control and get high maximum flows. Probably the one closest to your requirements would be the arctic cooling range of fans which are surprisingly quiet, affordable, thermally controlled and have a reasonable maximum flow (about 31cfm). The newer ones with the funky brackets are quieter.

dandragonrage · Post by **dandragonrage** » Sun May 29, 2005 1:56 am

I don't expect it to be quiet at max speed, but my UPS is an online UPS and always runs and so the fans always run. I don't even load it 10% normally, though, so it's not normally very loud anyway. But I am afraid if I put something with 30CFM in that if I should ever put more stuff on it and bring the load up that it won't be enough. I'm looking for a fan that'll be quiet "most of the time," not a fan that I will forget is there. (though that would be nice, but if it was possible, I figure Liebert would have put one of this in to start with)

ckolivas · Post by **ckolivas** » Sun May 29, 2005 2:23 am

As I said before, the combination of having high CFMs and thermal control is extremely unlikely. Your best bet is to put your own thermistor on a PAPST 8412NG which does 40CFM. They undervolt reasonably well. Are you sure you need 40 CFM?

dandragonrage · Post by **dandragonrage** » Sun May 29, 2005 2:25 am

No I'm not sure, but I don't want to find out by this thing overheating sometime.

ckolivas · Post by **ckolivas** » Sun May 29, 2005 2:31 am

I believe the medium speed Yate Loons probably also qualify (with a separate thermistor) but I have no experience or knowledge with them.

It may be worth getting your thermistor for the appopriate temperature range and just applying it to your current fans before trying any other fans. They might surprise you since most quiet fans are quiet because they run slower. The only thing that good quiet fans do extra is they can be undervolt to lower voltages and still turn and they don't click or buzz at lower speeds.

Post by **Ralf Hutter** » Sun May 29, 2005 9:47 am

These add-on thermistors are said to work quite well and can be used with most fans.

dandragonrage · Post by **dandragonrage** » Sun May 29, 2005 2:10 pm

Where might I find the medium speed Yate Loons?

Post by **NeilBlanchard** » Sun May 29, 2005 5:06 pm

Hello:

The Enermax 80mm thermally controlled fan is pretty darn quiet.

I have used it on a couple of different machines on an Alpha HS with the thermistor positioned in the exhaust air flow. The thermistor is the green bit near the 3-pin plug...it is on an 8 or 10 inch long wire, so you can position it to get the results that you need.