Ninja fan config question

where?wolf · Post by **where?wolf** » Sun Feb 11, 2007 2:59 pm

Just out of interest. If you have P180 case, and a Ninja.

The Ninja is ducted to the rear exhaust fan, (Noctua) running at 850 rpm. So is the top Noctua too.

If I where to add a 3rd Noctua to the heatsink at the same speed. Would the duct have any positive influence on the air flow / temperature? Or should it be removed. Then why?

If the duct should stay on? Then, should one of those fans rotate faster than the other?

cmthomson · Post by **cmthomson** » Sun Feb 11, 2007 3:30 pm

There is no reason to use a duct and two fans on a Ninja. A duct and one fan is all that is needed. I prefer to put the fan on the Ninja, blowing into the heat sink, and ducting out the back with no case fan. This has two advantages: it pushes the hot air off the Ninja directly out of the case, and it puts the fan far away from the case opening, reducing noise. For this duct to work properly, it must cover two sides of the Ninja, and be fairly well sealed at the back of the case.

This is all documented with photos in my DIY articles on SPCR.

where?wolf · Post by **where?wolf** » Sun Feb 11, 2007 3:54 pm

O.k. I see, with a duct and and a fan only on the Ninja. I guess you also actually get more air pressure over the fins this way too? Compaired to having the Ninja without fan and ducted to the rear exhaust?

And maybe better suction from the intakes?

Another cooling "problem", I have been pondering over are those vented PCI plates in the P180 B.

Do you think it's a good idea, to seal those plates except of maybe one below and one above the videocard for ex?

Or should one seal them all together?

It seems to me, leaving them all as they are. Will make the air pressure go downhill somewhat.

Thanks for your swift ansver.

cmthomson · Post by **cmthomson** » Mon Feb 12, 2007 3:41 pm

I think the idea behind the slotted PCI plates is that in a stock air flow configuration (no baffles, ducts, Kama Bay, etc), fresh air gets pulled into the case around the PCI cards (and therefore the video card) to help with video cooling. This also mitigates the fact that there are two case fans exhausting air that otherwise can enter through only one 120mm opening at the front of the case.

In a ducted/baffled configuration where the video and TV cards are cooled by an internal fan and the hot air is exhausted through the PCI slots above and below the TV card, the slotted blanks are not useful, and might actually reduce the directionality of the air cooling the card.

My system is older and does not have slotted PCI blanks. If it did, I would have taped off any still present, in order to channel the air flow across my TV card, which needs all the airflow it can get.

where?wolf · Post by **where?wolf** » Mon Feb 12, 2007 4:31 pm

Hi again!

Yeah, that makes sense to me.

Thanks!

Today I tried the air tight duct and the fan blowing over the Ninja with no exhaust fan.

But the strange thing is, that it cools very well that way. but I get the most annoying sound, that sounds like a pretty low, midrange "fridge" noise about. I tried the Noctua 1200rpm at both 850 and 1000rpm, The same with a Nexus and the Scythe fan that comes with the Ninja Plus. rev. B.

The Nexus got the best result. Noctua second. And the Scythe have a humming of it's own, even at 850rpm, that is quite disturbing to listen to.

But that noise, just at the edge of my hearing persisted.

I made sure the duct had rounded corners, and whas tight against the case / and Ninja. I have no sharp edges on the fan hole. And no fins are bent on the Ninja. I even turned off the top Noctua, and sealed the hole + put a thick book on top of it.

The stange thing, is that this noise where only heard in certain angles.

Any ideas what that whas?

Now I'm back, using the exhaust fan, (Noctua at 850 rpm) and the Ninja passive with the same duct. No such noise is present. Only a faint rush of air, that i can live with.

cmthomson · Post by **cmthomson** » Mon Feb 12, 2007 5:08 pm

where?wolf wrote:Today I tried the air tight duct and the fan blowing over the Ninja with no exhaust fan.

But the strange thing is, that it cools very well that way. but I get the most annoying sound, that sounds like a pretty low, midrange "fridge" noise about. I tried the Noctua 1200rpm at both 850 and 1000rpm, The same with a Nexus and the Scythe fan that comes with the Ninja Plus. rev. B.

The Nexus got the best result. Noctua second. And the Scythe have a humming of it's own, even at 850rpm, that is quite disturbing to listen to.

I'm guessing it's the blades of the fan interacting with the fins of the Ninja. I used two fan types on my Ninja: AcoustiFan DustProof and Nexus Real Silent. The AFDP had a definite thrumming sound that the Nexus did not (it sounded like a large very distant propeller aircraft). On close examination, I saw that the blades of the AFDP are closer to the downwind edge of the fan housing than with the Nexus, so with the Nexus, the fan blades are further from the fins. [Unrelated, the AFDP motor would resonate in free air, putting out a clear 450-Hz tone]

Here's a suggestion: try the Nexus, but at a lower RPM, like 650. It should still have lots of cooling, and the sounds should all disappear.

Another, completely different possibility: the duct might be buzzing or flapping. What is it made out of?

where?wolf · Post by **where?wolf** » Mon Feb 12, 2007 5:19 pm

cmthomson wrote:
where?wolf wrote:Today I tried the air tight duct and the fan blowing over the Ninja with no exhaust fan.

But the strange thing is, that it cools very well that way. but I get the most annoying sound, that sounds like a pretty low, midrange "fridge" noise about. I tried the Noctua 1200rpm at both 850 and 1000rpm, The same with a Nexus and the Scythe fan that comes with the Ninja Plus. rev. B.

The Nexus got the best result. Noctua second. And the Scythe have a humming of it's own, even at 850rpm, that is quite disturbing to listen to.
I'm guessing it's the blades of the fan interacting with the fins of the Ninja. I used two fan types on my Ninja: AcoustiFan DustProof and Nexus Real Silent. The AFDP had a definite thrumming sound that the Nexus did not (it sounded like a large very distant propeller aircraft). On close examination, I saw that the blades of the AFDP are closer to the downwind edge of the fan housing than with the Nexus, so with the Nexus, the fan blades are further from the fins. [Unrelated, the AFDP motor would resonate in free air, putting out a clear 450-Hz tone]

Here's a suggestion: try the Nexus, but at a lower RPM, like 650. It should still have lots of cooling, and the sounds should all disappear.

Another, completely different possibility: the duct might be buzzing or flapping. What is it made out of?

Yeah, that whas a better description of that noise than mine. A distant propeller aircraft.

Well, It took me several hours to do this test, and put everything back to as it whas before. But maybe later this wek, I will give it a new try.

The duct whas made out of pretty stiff, glossy cardboard. And I taped over every joint with duct tape.

What do you think about an Akasa amber, or a Aerocool 37 cfm Turbine?

Those fans seems to be good.

Thanks for your advice.

Felger Carbon · Post by **Felger Carbon** » Mon Feb 12, 2007 8:59 pm

where?wolf wrote:What do you think about an Akasa amber, or a Aerocool 37 cfm Turbine?

I'll butt in uninvited: the Akasa Amber is a ball-bearing fan. I bought one and it was incredibly noisy!

If the problem is interference between the fan blade and the Ninja fins, can you increase that separation by 1/4" or so? Means not using the wire clips, but round shoelaces work well (don't tell MikeC I said that).

where?wolf · Post by **where?wolf** » Tue Feb 13, 2007 1:56 am

Hi!

Yeah, that could do the trick. I will try it.

Thanks.

p.s I 'll be silent as a wall