Hi,

1st, I search the biggest available 12 V PC fan.
(If you know a fan (normally usage not for PCs) which is big and run with 12 V, it's also OK. ;-)

Not the biggest housing, the biggest radius of the rotor blades respectively diameter of the opening.

2nd, the best ratio: power consumption / performance (air flow rate).

Maybe you can help me?

Thanks.


* Best regards! :-) * Sutaru Tsureku, team seti.international founder. * Optimize your PC for higher RAC. * SETI@home needs your help. *

---

I can't recommend any of these since I'm not using such a monster, but that would be a good overview of large fans. The technical information to each of them contains the air flow and sometimes pressure, so I think you should be able to choose something from that. The largest are 250mm, however some of the 230mm has higher air flow rate.

PS: yes. it was indeed hot today in Germany.

---

I'm not sure specifically what you are after. You mention fan with the biggest possible diameter? That does not necessarily have anything to do with having the most airflow....

A large fan with low RPMs can quite possibly move LESS air than a smaller very high RPM fan... (The difference is typically noise, larger diameter fans produce less noise per air moved.)

If you are looking for maximum airflow, you need to look for fans with high CFM (Cubic feet per minute).

Here is a newegg.com search I did, only fans with the highest CFM are listed, highest price first.

(You will notice, the 120mm (and even 92mm) fans at the top of the list, push much more air than the 180mm/250mm fans under it...)

---

#resist

Other possible sources are industrial/maintenance supply houses such as Grainger.com or Newark, HVAC supply houses, or if you want something really big and noisy with high air flow to strap on the side of a case, 12v radiator cooling fans from an automotive parts supplier. But those are gonna draw some juice!

---

"Freedom is just Chaos, with better lighting." Alan Dean Foster

$14 at Lowes, drops temps 15C.

---

Executive Director GPU Users Group Inc. -
brad@gpuug.org

...But those are gonna draw some juice!

Yes, what Mark mentioned, or any of the high-airflow units from newegg I posted, will draw some serious current, regardless of the voltage... Make sure your PSU is up to par for what you are trying to do.

@Slavac: LOL! :-D

---

#resist

...But those are gonna draw some juice!

Yes, what Mark mentioned, or any of the high-airflow units from newegg I posted, will draw some serious current, regardless of the voltage... Make sure your PSU is up to par for what you are trying to do.

@Slavac: LOL! :-D

Of course, another PSU sparing option....run the high powered fans from the AC mains rather than using a 12v unit powered from the PSU.

---

"Freedom is just Chaos, with better lighting." Alan Dean Foster

...But those are gonna draw some juice!

Yes, what Mark mentioned, or any of the high-airflow units from newegg I posted, will draw some serious current, regardless of the voltage... Make sure your PSU is up to par for what you are trying to do.

@Slavac: LOL! :-D

It's ugly as heck, garish even, but good lord it's effective.

---

Executive Director GPU Users Group Inc. -
brad@gpuug.org

2nd, the best ratio: power consumption / performance (air flow rate)

In 1967, as a freshman at MIT, I took a survey course in aeronautics taught by a grand old man of the department (Otto Koppen--designer of the Helio Courier). One of the precepts he taught was "grab as much air as possible and do as little with it as possible".

While fans do vary in how well they are shaped, how efficient their motors are, and such, in general you are likely to find that both noise per unit airflow and power consumption per unit airflow will be superior on large diameter fans moving slowing than on small ones moving fast.

Watch out for noise, in particular. The fan people have a funny way of measuring it, which means that even 30 dB is readily audible. So when one admits to 66.5 dBA (as does the top one on that NewEgg list), it quite likely is a real screamer. That same fan admits to pulling 48W, or 4.8 Amps out of the 12V supply.

Of course, if you don't care about noise, power, or efficiency, you can move a lot of air with a really small fan turning at a screaming rate. Check out the things they put in slender server cases. A really good programmer I know had a boss who as a special favor arranged to get a server PC for his office. He first disabled half the fans (it bragged of having redundancy, so cooling would be adequate with multiple fan failures), but still could not stand the noise level--the thing got banished to a machine room.

---

...But those are gonna draw some juice!

Yes, what Mark mentioned, or any of the high-airflow units from newegg I posted, will draw some serious current, regardless of the voltage... Make sure your PSU is up to par for what you are trying to do.

@Slavac: LOL! :-D

It's ugly as heck, garish even, but good lord it's effective.

And you forget to tell, uses no power from the computer PSU.

---

I just bought 2 SilverStone 180mm Air Penetrator fans (model no. SST-AP181) and modded 1 of my old Antec Titan 650 server cases with 1 fan in the top, the other in the side over the video cards.

With these fans there is a grill built in on the outlet side that directs the air straight instead of letting the air fan out and these can run at 7V (80cfm, quiet) or 12V (130cfm, noticeable) but they have improved the case cooling dramatically running at just 7V.

Cheers.

---

(If you know a fan (normally usage not for PCs) which is big and run with 12 V, it's also OK. ;-)

I happened to stumble on an Anandtech thread where a similar question was posed. I'll quote an answer given there (can't vouch for veracity myself)

For a 12 Vdc fan that big try an automotive radiator fan like this...


here are the specs


Product Features
Universal for all vehicles (Measure your radiator before purchasing)
Package includes: 12" Blue radiator fan w/ 4 clip on brackets
Efficiently cool down your radiator
Light weight & slim design allows more clearance for other aftermarket engine components
CFM: 1550, ~2200 RPM, 12 Volt, 8 Amp, 2.5" Thick, 12" Dia.

This image and these specs appear to have been found by the person posting on Anandtech on an Amazon listing. If you type "12V radiator fan" into Amazon's search window, and restrict the answer to Automotive--you'll see quite a few offerings. Just possibly something there might suit you.

Going back to my power efficiency comments, while this one is nearly 100 watts, it claims many times higher airflow than the 48 watt fan at the top of the Newegg list.

---

The noise should be awesome.

---

An automotive HVAC blower motor (squirrel cage fan) can move some air if there's a junkyard near you.

Have a look at automotive fans, they shift some air, most are 12V (avoid trucks and RVs which are often 24V). But they do draw some current, don't be surprised at tens of amps if you got up to 500mm or more!

---

Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?

1st, I search the biggest available 12 V PC fan.
(If you know a fan (normally usage not for PCs) which is big and run with 12 V, it's also OK. ;-)

As others have mentioned, car radiator & airconditioner condenser fans.

---

Grant
Darwin NT

I bought some Multicomp, MC21710, 120mm, 12V, 1.6A, 190CFM (approx 5.5M^3) fans a while back.

Running on 12V they sounded like a fire siren, but feeding them from 5V they are much quieter and still push enough air to cool 3 x GTX470's in summer.

I have also used Slavac's method with good results too.

T.A.

I guess how you want to use the fan really comes down to what you really want. I have some 120vac 120mm fans that probably move several hundred CFM, but they make about as much noise as a 474 taking off from the runway. I was using them to cool my Celeron 333MHz with a sandwich cooler to get it up to 666MHz.
Later I got a commercial 30" air circulator. Which I placed on the floor by my desk and had it blow into/through the case. Made less noise and was as effective.

If you have a limit on the amount of noise you are willing to tolerate then you can find the highest volume fan that makes that much or less noise.

A squirrel cage/centrifugal fan might also be something you want to look at.

---

SETI@home classic workunits: 93,865 CPU time: 863,447 hours
Join the [url=http://tinyurl.com/8y46zvu]BP6/VP6 User Group[

As a retired electronics engineer I cannot recommend running fans below their nominal voltage. Expecting a fan to start at half voltage a few years down the road is only asking for trouble.

If you want a DC fan to run slower use a PWM controller. A PWM controller runs the fan on pulses of 12V, the width of the pulses being proporional to the required speed.

@Slavac: Well played, sir. Well played :D

---