Is 110.31CFM Overkill for an exhaust fan?

[napes22]

Would you say that is a little overkill? I could use more airflow in my case (using a Scythe S-Flex 1600rpm in the back which pushes 67CFM at 28dba). My exhaust fan is currently on the way out (had to tape the connector to keep it going) and really doesn't move enough air to keep my system cool.

New Scythe Fan Specs

Is the 1900 RPM (110.31CFM) fan overkill for a upper-mid range gaming pc - would the 1600 (88.11CFM) suffice?

Thanks.

 

[VinDSL]

I think a Shop-Vac would be overkill!

Put another way, I don't think 110CFM vs 88CFM makes any difference (on exhausts)...

 

[napes22]

Does that mean I wouldn't see much of an improvement between the 88 and 110? or that as long as can put up with the noise put as powerful a fan I can get my hands on?

 

[Zepper]

The slow one would change the air in the case at least 30 times per minute and the fast one at least 40 times per min. Just depends on how fast you want your case to fill up with dust.

.bh.

 

[napes22]

I never realized that aspect of fan speed. In terms of cooling though - My CPU fan blows towards my exhaust fan - would the difference in fan speed make a big difference in cooling?

 

[Zepper]

Just calculate the cubic feet of space in your case and divide that into the CFM of the fan and you have the changes per minute. That's a rough value because there are solid objects in the case taking up some of the volume in most cases, so you'll actually be getting many more changes per minute. I don't think you'd get the extra noise's worth of extra cooling. Just be sure that you have enough intake available (either by fan or vent area) to allow your new fan to actually move the air it's capable of. Check the RPM of the fan in open air, then put it in the case, button it up as it would normally be, and measure the RPM again. If it slows down at all, then your intake air is lacking.

It looks like the only other opening in that case is in the top. Is that for PSU air intake or is it just a vent or is there an exhaust fan there. The last thing you want is air coming in and then going directly out the rear exhaust w/o having done any cooling work.

.bh.

 

[jmmtn4aj]

Originally posted by: Zepper
Check the RPM of the fan in open air, then put it in the case, button it up as it would normally be, and measure the RPM again. If it slows down at all, then your intake air is lacking.

I never really delved into the technicalities of fan design.. A powerful exhaust fan and a weak intake fan would mean negative pressure in the case, wouldn't that allow the intake fan to spin faster due to autorotation?

 

[napes22]

I have an exhaust fan up top - and my intake fan is also 67 CFM. Would I be better off replacing the intake and the exhaust with the 88CFM fans to create balanced airflow? The new Scythes are oddly affordable (like 10 bucks).

 

[napes22]

bump?

 

[DrMrLordX]

Why don't you just a 110cfm fan and run it as fast as your case needs it to go with a fan controller or something like speedfan.

Alternatively you can get the Silverstone FM-121 for around $14 that comes with its won fan controller and will also push 110cfm.

 

[tno]

The balance of quiet and cool is hard to find. I'd say if your temperatures were good before then aim for the quietest fan with the same CFM, if you find a fan that blows more air with equal dBA then you might get better cooling but if your cooling wasn't bad before then it'll be a negligible improvement.

If you're thinking of changing all your fans I'll give you this advice, the best fans can operate at 5V, that is, the lowest voltage your PSU supples is enough to spin the fan. This demonstrates the fans efficiency and ability to translate little energy into revolutions and gives you the full range (5V - 12V) to, using a fan controller, find the exact speed that gives you a balance between cooling and silence. Good luck, let us know how it goes!

tno

 

[Arcanedeath]

For 120 mm fans aprox 1200 rpm is as fast as you want to go for quiet 800rpm is pretty much silent about 1600 rpm is very noticeable but still tolerable and 2000+ rpm cools great but isn't for anything except benchmarking, most 120mm fans sound about the same so buy based on the RPM and use a fan controler if you have to to get the noise where you want, I find 1200 rpm to be a good mix of cooling and performance.

 

[tylerdustin2008]

No way in hell does that Scythe push 110 cfm at 37dba, add 10 that.