fan choices and db help

[kcbass]

I'm looking for a cpu fan for a thermalright SI-128. It'll be going on an asus p5b deluxe with an e660 c2d. Here are the models I was considering:

http://www.coolerguys.com/sff21.html
http://www.coolerguys.com/840556026129.html
http://www.coolerguys.com/840556021476.html
http://www.coolerguys.com/840556001058.html
http://www.coolerguys.com/840556001096.html

I've made a chart of cfm vs db, and it's fairly linear, but I don't know what is considered adequate cfm, and acceptable noise level. Can anyone point me in the right direction? I know there are probably hundreds more fans out there I could consider...any really great ones I've missed?

 

[tylerdustin2008]

Id go with Scyth if you are willing to pay for it.....

 

[kcbass]

which rpm model?

 

[tylerdustin2008]

the highest one.

 

[Nickel020]

This Yate Loon is one of the best fans out there:
http://www.coolerguys.com/840556021537.html
It's actually the same as the Nexus that costs $10 more, Nexus just rebrands fans.
http://www.coolerguys.com/840556054078.html

 

[yosuke188]

Originally posted by: tylerdustin2008
the highest one.

I would recommend the highest one too if you have a fan controller. If not, then go with the middle one, or the lowest one if you want absolute silence.

 

[kcbass]

I had actually ruled out the yate loon and nexus fans because they push less air and are louder than the scythe 1200 rpm model.

I do not have a fan controller, so how loud would the different scythe models be in a system? Also, would the mid and lowest models push enough air for a cpu fan?

 

[kcbass]

It's interesting....according to my chart, the lowest rpm panaflow is 100 rpm slower than the fastest scythe, but pushes 5.2 more cfm for only an additional 2 db. It's a little messy, but I thought I'd include it anyway

FAN RPM CFM DbA price

scythe 800 33.5 8.7 15.95
scythe 1200 49 20.1 15.95
arctic 1500 56.3 23.5 7.95
scythe 1800 63.7 28 15.95
panaf 1700 68.9 30 16.95
panaf 2100 85.5 35.5 15.95
panaf 2750 114.7 45.5 16.95

 

[MJGlo]

I'm using the Scythe S-FLEX SFF21D 120mm Case Fan 800rpm version on my CPU and for case exhaust. My CPU temp. hangs around 35c. to 39c. while running it at 2.6ghz.
I don't hear this rig run.

 

[kcbass]

so 33 cfm is enough for a cpu fan?

 

[MJGlo]

Originally posted by: kcbass
so 33 cfm is enough for a cpu fan?

In my case 36c. is cool enough with a 800rpm fan, if that temp is too hot for you then 33cfm is not enough.

 

[kcbass]

According to speedfan, at full load my current cpu temp is 46 and my case temp is 38, but that's with son to be old cpu and mobo, msi k8n neo2 plat with an amd 64 3200. I plan to also add an 8800 gtx which I've heard runs really hot.

 

[RallyMaster]

Yate Loons are not loud. You need to hear it to believe it. Decibel ratings don't mean a thing these days because all manufacturers lie. YLs move air very quietly and I'll be damned if you're annoyed from hearing them 3 feet away in a closed case.

The spinning of my hard drives make a lot more noise than my YLs do, just to give you a taste.

 

[kcbass]

Yeah, my hard drives are getting replaced too...one won't stop spinning and it's driving me nuts.

The fan I'm currently using:

http://www.coolerguys.com/840556054061.html

It's operating at 27 cfm for 19.2 db, so the slow scythe would be more airflow and 8 db, which means that any fan on the list would be a vast improvement with cfm, but most would be an increase in noise. Not a lot, but still an increase.

At this point, I think I'm leaning towards the slow or mid scythe, but still not sure which way to go.

 

[RallyMaster]

I'm still going to say go YL. I honestly don't think the change in noise is worth the 10 dollars more you'll be spending on a Scythe...

 

[Navid]

dBa is a logarithmic unit. CFM is a linear unit. So, charts or curves or ratios of CFM over dBa are all useless.
In addition, there is no standard that the fan manufacturers follow for measuring their reported dBa figures. That is why you should not base your decision on those dBa numbers.

Edit:
Some reading on dB if you are interested.
http://www.phys.unsw.edu.au/jw/dB.html

 

[kcbass]

I know much about the decibel curve and the logarithmic scale, I'm an engineer. What I don't know is the correspondence between a decibel measure and what it actually sounds like.

Here's a better link for db as it applies to case fans and its relationship to cfm:

http://www.endpcnoise.com/cgi-bin/e/decibels.html

 

[Navid]

I saw this post by you.

Originally posted by: kcbass
but pushes 5.2 more cfm for only an additional 2 db.

Considering that 2dB is actually a lot louder, I assumed that you may not know what dB is all about.
My mistake!

 

[kcbass]

Yeah, sorry. It is only 2 more db, but when calculated it actually shows as 1.2 times louder. I didn't make that clear.

 

[kcbass]

So, with computers what db levels are considered silent, quiet, normal, loud, and very loud?

 

[Navid]

Originally posted by: kcbass
So, with computers what db levels are considered silent, quiet, normal, loud, and very loud?

Silent PC review is a good place for reference.
http://www.silentpcreview.com/section5.html

What is quiet and what is loud depends on your point of reference.
It depends on your environment.
It depends on what else is running in your PC.
It depends on what frequencies you are sensitive to.
And a lot more!

That's why it is better to get a fan that is recommended and work on it from there. You can reduce the RPM using a fan controller to adapt it to your system.

There is often one offending fan. No matter how quiet everything else is, it is always the loudest fan that you hear. Find it and work on that.

I spent a lot of time on that. Be careful; there is no end to it! You will always find something that you want to make quieter!

At the end, I just moved my PC away by about 8 feet to the other corner of the room. It is absolutely silent now for me even though the PC is not. I use a 15-foot DVI cable for my graphics. Since it is digital, the length does not degrade performance.
My monitor includes a USB hub. That makes it easier.

You can get cables for cheap from http://www.monoprice.com/home/index.asp.

 

[kcbass]

Originally posted by: yosuke188

I would recommend the highest one too if you have a fan controller. If not, then go with the middle one, or the lowest one if you want absolute silence.

Can you recommend a good fan controller? I think this route may be a good idea, that way I can have the advantage of the quiet at the slow speed, or the additional cfm if needed.

 

[Navid]

I would get a simple one with 4 knobs.
I would stay away from the one that goes all the way down to 0V (http://www.svc.com/bus-55-sl-24.html), or something low enough that could stop the fan.

Make sure it works even if Windows has not come up yet!
Don't get something that needs a software utility to run in order to work.
I am sorry I cannot give a direct recommendation because the one I have is not sold anymore (Aerogate 1).

Edit:
Cut and paste the link if it does not go there directly!

 

[kcbass]

I saw that one, but I was actually looking more at one of these two:

http://www.coolerguys.com/840556020349.html
or
http://www.coolerguys.com/sun20in1.html

Just trying to figure out if I want it in a large bay or small bay, but I like the status lcd.

 

[Navid]

My problem with the controllers that go all the way down to 4V is that if some day someone else is using my PC and turns one of the knobs all the way down, the fan will stop.
If the CPU fan is also controlled this way, I would not want that possibility to exist.