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Ok, another fan dilemma. Need some input.

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Brutal-Force

Brutal-Force

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Joined
Feb 22, 2009
I am running my Push/Pull Panaflos. 2600 RPM versions. On the Fan Controller they only hit 2400 RPMs no big deal.

Here is the problem. When I turn the speed all the way up, the rear Coolermaster 140 mm fan picks up air resistance and appears to slow down.

Judging by the Fan speed program though, the speed remains constant.

The rear fan is only a 700 RPM fan and I am running the 38mm Panaflos in push and pull putting the "pull" fan 2-3 inches away from the rear case fan. Would I be better off removing the rear fan all together? Could it be causing an obstruction? Do I need to put in a faster 140mm Case fan? If so, which. From all the 140s i see Noctua has the fastest one at 1300 RPMs, but I don't have any clue.
 
Edit that. Read wrong. You have >fan> HS >fan> empty space >fan> rear-wall-of-case, with the > pointing in the air-flow direction, right?
 
Yes. Its just that the Panaflos are just that much faster than the Coolermasters.
 
Is this your Panaflo?

The 140mm Noctua fans are great if you want quiet. For CFM, not so much. Their site measures in cubic meters per hour, which is nearly double what the number would be for cubic feet per minute. The NF-P14 only hits ~65 CFM, which is half what a 2500+ RPM Panaflo does.

This says 73CFM.

Or, you could use this and just stick another one of the same model Panaflo on the case.
 
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I have the 120 mm versions, so I am well aware of where the Noctuas are lacking. I replaced my CPU cooler Push/Pull Noctuas with Panaflos.

The last tip may work. Its too bad they won't be as quiet. :/

Thanks you petty.
 
Hey Brutal, why not just pull the rear case fan and see how it goes? It might just work out fine without the rear case fan, since it sounds like the Panaflo fans are pretty well lined up with the exhaust fan. If that does ok, you might even think about ducting the rear Panaflo to the exhaust hole. It's worth a try to see how well that works and only costs a little time.
 
I wonder if I use a 4" PVC Pipe cut to size, Paint it black. Put a Flange on it.
 
Yeah, you could do that. But TR makes a very nice duct that you could easily adapt for this and is pretty inexpensive too. Just reverse it around and then cut off the end that would normally fasten to the HR-01 heatsink and pass that through the case hole.
 
Would the HR-01's dimentions be 140mmX140? or 120X120? I would think it to be just a little larger than 120X120. If its 143mm in length then it is what, just shy of 6 in.? It might just reach from my rear Pull fan to the back of the case. Good call.
 
I think I am going to try putting the two Noctua Fans in. One in the back to replace the slow 140 in there and one in the bottom. They are the NF-P12 with High static pressure, so they should move a lot of air with minimal silence. They are also the 1300 RPM versions which should cut down on some obstructions.
 
With those big Panaflos, there is no way any rear fan will keep up. Ditch the rear fan, and cut out the grill. That way your exhaust will have a free path outside the case.
 
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I put in the Noctuas. I tried without a back fan, but the air does not go straight for th back of the case. EIther I am going to have to stick in a duct or keep a fan in the rear. Fortuantely the Noctuas are a) quieter than the Coolermaster Fan b) run at a higher RPMs and do not slow down when I turn the Panaflos up.
 
I moved my rear case fan to the outside of the case. It works the same, but gives more space in the case in that tight area. It might help you out as well.
 
I have a similar situation (Although I only have a single 120x38mm San Ace in pull. It was really close to the rear case fan. The San Ace is so much more powerful that it was making the rear fan spin faster than it should, and was causing extra noise.

I just removed the rear fan and now my San Ace blows nicely out the rear exhaust. It works just fine! -Although I DO have 2x 140mm fans blowing out the top to get rid of the rest of the case's warm air.
 
Remove the rear fan and duct the pull CPU heatsink fan to the place the rear fan was.
Less restriction, plus all the hot air off the cpu heatsink leaves the case.
 
Push? Where? In what direction? Most of us put a push fan on the front side of our cpu cooler, and sometimes we put a pull fan on the back of our cooler. Occasionally people reverse the direction. If that's you, then a push fan in the back is fine. But still, delete the grill.
 
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