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Looking on Advice on Case fans. Whats a good CFM/db balance?

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February 8, 2009 4:54:00 AM

I've got a nice cooling system set up with my computer. I have the Cooler Master Centurion case with a front 120mm fan, and I've installed a 120 mm on the back for the "wind tunnel cooling."

One was one that came with the case. On the back went a Thermaltake A2368 with 78CFM. It was advertised as being quiet. Clearly they lied about their specs, becasue it has a noticeable whine, and is what I would call a loud fan. The hum is greatly amplified when it touches the case. I've tried putting cut foam behind it, but it sill resonates nicely. Its not terribly loud, but it gets inside my head.

Then I added an 80mm on the side to blow fresh air on the CPU, and its really helped out my temps, but its a noisy fan too. It has quite a hum to its operation.

Now I understand I have a loud video card, but at idle its really not so bad. However my fans are driving me crazy. I spend many hours a day sitting next to my computer, so the noise has plenty of time to get under my skin. Right not its not so much a whooosh, but a resonate hum.

So I'm trying to find new fans. I want to strike a good balance between silence and airflow.

I think 20-30db is bearable. I don't mind the white noise from pure air flow, but the hum of the fan's motors does get annoying.

So what are good fans? I'm thinking of replacing my 2 120's and getting an 80mm. I'm also thinking of using rubber plugs to mount them. I also want no LED's on my fans.

I noticed the noctua fans looked pretty solid on the balance between noise/flow, but are pricey.

Also I really don't know what a "good" CFM is. I see many 80mm are around 20-25CFM with db a few digits lower.

I hear lots of people say "oh these are quiet" I have a hard time knowing if I'll find em quiet. For all I know they could be people that got used to a windtunnel. I'm looking for something on par with my stock AMD cooler fan. Something that when I close up the case I can't really tell they are there. Any help I could get would be appreciated. 2nd and 3rd opinions are welcome.
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a b B Homebuilt system
February 8, 2009 6:59:00 PM

I like the Scythe SFF21E
February 9, 2009 4:07:35 AM

I replaced the stock CoolerMaster fans in several Centurion 590 cases with Scythe S-Flex SFF21E, 1200 rpm fans. I also installed them on tower style cpu heatsinks. They turned out to be a very good compromise.

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

The problem with noise is that one person's quiet fan is another person's jumbo jet engine. I've read enough threads at this forum to know noise is relative. In my case I normally listen to an Internet radio station so I don't hear the noise at all.
a c 122 B Homebuilt system
February 9, 2009 12:22:08 PM

Yes, noise is relative, but there's no way that a 12 cm. fan moving moving 78 CFM is going to be quiet.

I'm using an S-Flex SFF21F on my TRUE. Max speed is 1600 rpm. Moves about 65 CFM at max speed - what I regard as a good compromise between noise and airflow. It's in an Antec case with the case fans set on LOW. Even with a heavy CPU load, it never spins up to medium speed.
February 9, 2009 8:22:33 PM

Do you have any control system in place for your fans? Generally, most machines do not need their cooling system at full power most of the time, and when they do they are normally either doing something distracting (gaming) or something you can get up and leave during (video encoding, etc). Does your motherboard support lowering the power to it's 3-pin fan headers based on case temp? If so, you can give that a try. Fan control panels can also work.
May 5, 2009 6:52:41 AM

Thanks everybody for the replies, I bought some coolermaster 120mm fans on newegg...about 40 CFM. They were the standard no-LED style came in a set of four, and they are quite quiet enough for me. They replaced the LED fan that came with the case, and the noisy Thermaltake. They were rated about 20-30 db and I really believe it.

I also bought an enermax 80mm fan for the side of the case to push cool air on the cpu, as that seemed to drop my temps ~5 degrees. Its also much quieter than the old raidmax fan it replaced.

Add in my upgrade the newest EVGA GTX 260 (that has a suprisingly quiet cooler when left on automatic mode, and I have a nicely quiet case. God damn my old ATI cooler was whiny. The only thing I hear now is the resonance of my one hard drive that's mounted directly to metal, and very light whoosh of air.

I'm pretty happy with it all as it allows me to leave my PC on at night and actually be in the dark.

And given all that I now consider my question long answered.
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