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Noctua fans not good for exhaust?

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July 15, 2008 3:31:09 AM

I bought a 120mm Noctua NF-P12 to replace my slow and weak Enermax enobal. Well, there is no difference in exhaust "power". What I mean is there is no more air coming out the fan as there was with the much lower CFM Enermax fan, its the same. The fan is facing the correct way its just not pulling out any air, what gives?

Just like the Enermax fan that was in there before this, the fan appears to be moving extremely, extremely slow, id say 400RPM. I can actually see the fan blades and make them out from the shadows, and if i cover the exhaust with my hand the fan obviously appears to struggle, changing speed. Would this be due to how I have it hooked up, a 3pin extention cable going to a 3pin to 4pin molex adapter which is pluged into a bunch of other crap. Should I try hooking it straight into the motherboard?
July 15, 2008 3:48:04 AM

spathotan said:
I bought a 120mm Noctua NF-P12 to replace my slow and weak Enermax enobal. Well, there is no difference in exhaust "power". What I mean is there is no more air coming out the fan as there was with the much lower CFM Enermax fan, its the same. The fan is facing the correct way its just not pulling out any air, what gives?

Just like the Enermax fan that was in there before this, the fan appears to be moving extremely, extremely slow, id say 400RPM. I can actually see the fan blades and make them out from the shadows, and if i cover the exhaust with my hand the fan obviously appears to struggle, changing speed. Would this be due to how I have it hooked up, a 3pin extention cable going to a 3pin to 4pin molex adapter which is pluged into a bunch of other crap. Should I try hooking it straight into the motherboard?


With the case open, what does either fan do? What I'm getting at here is that if you have a well-sealed case and a restricted intake fan, your exhaust fan is soon going to be working against negative pressure.
July 15, 2008 3:57:39 AM

Preasure is the problem i think, you said it. I have a Raidmax Smilidon, I have two of the 120mm Enermax Enobal Marathon fans as front intakes, both are preety damn restricted.

The top front intake is on a Thermaltake iCage "cooling" 3 harddrives, there is no air comming past the drives obviously. And the bottom intake has a basic plastic grill with 1mm holes, while the grill behind that fan has 3mm squared holes so VERY restriced as well, using my hand I felt ZERO air comming from this fan. With all that blockage I dont think any fan up there would make a differnece.

On the side pannel there are two 80mm fan holes, one uptop inline with the CPU , I have no fan here its a open vent, and one on the bottom of the side pannel inline with the video card, I have a 80mm exhaust here, also a Enermax Enobal Marathon.

And of course the rear exhaust is the 120mm Noctua, which has the fan from my Xigmatek 1283 "blowing" towards it, keep in mind there is ZERO air comming from the back of this cooler, which has me thinking the intake fan dosent have any air to pull in the first damn place which also explains why no air is comming from the exhaust......no damn air TO exhaust. Also my 580W Mushkin PSU has a 120mm exhaust up there.

This is beyond frustrating. I really dont want to have to get a new case and I know I shouldnt need to. My CPU (sig) idles at 45c with the Xigmatek 1283 which is pathetic and laughable.

**EDIT** Opps forgot to mention. WHen I take the side pannel off temps drop a rough 5c across all 4 cores. GPU drops 2c. Unplugging the CPU fan completely only raises temps by 2c after 5 minutes of idle use, its obviously doing jack ****.
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July 15, 2008 4:14:18 AM

Make both of the side fans blow as intakes (80 mm fans are pretty cheap) and see what happens. Remove the restrictions on the bottom intake. Plastic is easy to get rid of, the holes behind the fan may require some more creative measures... Scroll saw? Dremels make a hell of a mess...
July 15, 2008 4:17:46 AM

That 'extension cable' you used is the problem, it is Noctua's ULN (ultra low noise) cable, it undervolts the fan so you get way less RPMs (notice the bump under the shrink wrap, its a resistor). Try not to use that if you want to max out the fan, still those Noctua's don't push a lot of CFMs, but they are quiet for how much they do. The price you pay for silence! Always compare noise, RPM and CFMs amongst fans. I prefer to use a goof fan that can push a ton of air and use a fan contorler for silence when I want it.
July 15, 2008 4:19:15 AM

I have another 80mm laying around, ill throw it in the top hole as intake and flip the bottom one around tomorrow. As far as the bottom intake goes I could probably pop out the outside plastic screen, but the inside one will require metal fabricating like you said, ill buy a $120 Antec 900 before I do that.
July 15, 2008 4:20:13 AM

badgtx1969 said:
That 'ectension cable' you used is the problem, it is Noctua's ULN (ultra low noise) cable, it undervolts the fan so you get way less RPMs (notice the bump under the shrink wrap, its a resistor). Try not to use that if you want to max out the fan, still those Noctua's don't push a lot of CFMs, but they are quiet for how much they do. The price you pay for silence! Always compare noise, RPM and CFMs amongst fans. I prefer to use a goof fan that can push a ton of air and use a fan contorler for silence when I want it.


Its a standard extention cable, 3pin. I didnt use the LNA or the ULNA in the box. Regardless I took it off the extention and pluged it right into the mobo and the RPMs did actually go up.
July 15, 2008 4:21:51 AM

What are your RPMs then?
July 15, 2008 4:23:53 AM

948RPM according to HWMonitor, 300+ below spec still.
July 15, 2008 4:28:36 AM

Yeah it should be around 1300, right? Double check w/ another program and plug into another MB connection. Might be a bad fan, which sucks for how much you pay for those things.

Your getting ~37 CFMs when it should be ~54 CFMs.
July 15, 2008 4:33:59 AM

Actually croc I cant put a fan in the top side slot due to the Xigma cooler, its basically touching the side, 1in off it.

And yes 1300RPM, its currently in the chassis fan plug, putting it in the PWM plug right below it slows the fan down although I cant get a reading off it with HWMonitor or speedfan.
July 15, 2008 4:43:17 AM

Also from time to time there is a pulsing noise/vibration comming from the case, im assuming its fans getting their asses beat by backpreasure.
July 15, 2008 6:32:37 PM

I went ahead and said screw it and bought a NZXT Tempest. Its basically their version of the Antec 900, but with better airflow, more interior room and better wire management. And it was $10 cheaper.
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