Problems fitting Noctua D15 in case with desired fan layout - can one put 2 fans in line?

[PeterZ640]

Hmmm trying not to lose my top PCIe x16 slot.
Looks like there wont be enough room to place my D15 vertically and have two additional 140mm Noctua fan above that.

If I moved one of them towards the front I need to use the other one as an exhaust.
The question is can I have one 140 exhausting out of the back, and on the other side of the rear wall place the 2nd one sucking air out of the case - effectively having 2 directly in line with just the case wall (1mm perforated steel) in between them.

Would it set up some kind of weird turbulence or noise?
I could use the attenuator on the inner one so it maxes out at 1200 rpm and leave the outer one running up to 1500 rpm so the second one doesnt "choke" the first. Is that an idea?

Interested in hearing from anyone who has played about with fans.

I would do it myself, but any adjustments mean taking out the cooler to reorganise the fan layout.
Time is against me as I have £2,000 worth of components I need to set up and test out before my 14 day period runs out in case anything is D.O.A..

I views welcome.

My goal is to have 5 x 140mm and 1x 120mm ( plus the two 140s ) on the cooler; but running really slowly so I get a lot of cool air flowing through but low noise because they are running slowly.

 

[PeterZ640]

http://i1379.photobucket.com/albums/ah159/Submariner5DIII/image_zpsbqook7km.jpeg~original

Might help explain idea is to take top left roof fan and bolt it outside the case on the rear wall opposite the existing rear exhaust fan

 

[PeterZ640]

http://i1379.photobucket.com/albums/ah159/Submariner5DIII/Supermicro%20Workstation/image_zpssvspqi6i.jpeg~original

 

[gondo]

Having 2 fans in line is a push pull configuration. It's been done and not a big deal.

My guess would be to have the heatsink horizontal with the fans facing left to right, not top to bottom. This allows 1) not to cover the top PCI-E connector, and 2) to not hit the top case fan.

So putting the heatsink horizontal you have the center fan, and the fan on either side of the heatsink. If you put the heatsink fan on the left then it hits the rear case fan. Also any cool air entering the case may be stolen by the top fans before it has a chance to hit the heatsink. By have the heatsink fan on the right any cool air travelling up from the front of the case will split and exit through the heatsink fan and the top fan. This may also allow room for the fan on the rear case. Ideally you don't want fans on the outside of the case then they are open to fingers, cables, and dust getting caught, unless you get grills for them.

You could try both ways and see which is more effective.

My gut instinct is telling me to eliminate the 2 top fans. Have the fresh air enter the front of the case, and have it rise up through the heatsink and out the back. No top fans. With 2 intake fans, and 1 exhaust it creates positive air pressure to eliminate dust in the case. With the top fans you'll get lots of negative air pressure and pull dust in through cracks near the optical drive bays. It also looks like your PSU has the fan facing down assuming you have a grill cut out for the fan. So it just intakes air and shove it out the back. If the PSU fan is facing in the case, it acts as an exhaust and you definitely want to remove the 2 top case fans.

So my first thought is to remove the 2 top case fans, have the heatsink horizontal with 1 fan in the middle and 1 to the right, both blowing air towards the left and have the rear case fan exhaust. You'll basically have 3 fans lined up blowing air towards the rear. This should create good heatsink flow and some positive air pressure within the case. The intake fresh air will rise with some being stolen by the video card and the rest enteting the heatsink and exiting the back.

 

[Bearmann]

PeterZ640,

I can see that this is your fan fantasy , however, I think you may do better with 2 front case fans,1 rear case fan, and the D15 in a conventional horizontal layout. Leave the front roof port open, but unoccupied. Do you have more than one GPU? Here is some food for thought:

http://www.bit-tech.net/hardware/2012/02/10/the-big-cooling-investigation/1

https://www.youtube.com/watch?v=8OmkmluAYAQ

 

[PeterZ640]

Hi Sprinter and Bearman
Thanks for your detailed advice.
Just a couple of things. My initial plan was to have, 2 x 140mm in from the front, and the D15 horizontal with its 2 fans pushing air to the rear 140mm.. Then to reduce the speed of the fans and thus noise level, I re-engineered the case to have 1x 120mm in the front - mainly to increase positive pressure ( reduce dust).

I had miscalculated, that this lovely board with 3. X16 Gen 3 PCIe slots has the top slot very near the CPU.
Hence I had to turn the cooler vertically as that gave me 9mm more clearance fromthe top PCIe Slot. Hence I now have 7mm clearance instead of covering it by 2mm.
So vertical it has to be.
Although there are 2 upward roof fans , there are very small vents at the side of the roof chamber.
Actually spent today cutting a stainless steel panel to block off the 3rd roof fan slot. As I suspected the hot air suckwd up probably found its way back into the case rather than exiting via the 5 thin side slits about 40mm x 4 mm on each side.
So although I have 2 x 140 in and 1x120 in and 3x 140 mm exhaust ( 2 of those are trying to force air out of thin slits. Hopefully this increases positive anti dust pressure.
My core temps are between 36C and 37C under load and the package temp is 42C
Hopefully the new roof venting panel will reduce temps more, but wont help dust :-/

The psu draws air in from a filtred floor hole , and blows it out the back. None goes into the case. There is a gap of about 10mm all around the psu casing, that the lower front intake fans blow air over the psu case and out the back
It actually stays off most of the time, only under load does it come on.

So Far seems to work at these temps with fan speeds of 350 rpm which is pretty quiet despite having 8 going.
My only issue is under medium load, the MB tels the 2 Cpu cooler fans to speed up to 900rpm, but as the case temp is only 27C the roof fans are dictated to run at 350rpm.
And that inbalance of 2 cooler fans pushing air up at 900 rpm directly into say one and a half fans funning at 350 sets up a slight turbiulance noise.
Under stress testing then the other fans sometimes speed up to 900rpm and the turbulance noise goes away. So I am pretty sure this is the issue. It is not bad , just spoils the perfect quiet case, that has potential to create a hurricane with 8 highly efficient Noctua 140mm fans running at 1,500rpm .

I am looking into hooking up the roof fans to the same cpu fan header as the cooler so when the cooler goes to900rm so would the 2 roof fans. Pretty sure that would solve it.
Just need to checkmI can use 2 Y cable in series, and if the CPu fan header can support 0.88 amps (i.e.m4 x 0.22A).
In one respect not perfect as if the CPU fan header ever died, then the roof fans currently off Fan Header no 2 would deliver some drw throughthe cooler heatsinks.

o Wish SM MBs had more fan control options in the bios etc.

 

[Bearmann]

Oh, SuperMicro motherboard. I'm glad it is working out. Maybe some resistors to limit those problem fans top speed, if it is safe to use those with the Y, or Y on Y connectors.

 

[PeterZ640]

Oh, SuperMicro motherboard. I'm glad it is working out. Maybe some resistors to limit those problem fans top speed, if it is safe to use those with the Y, or Y on Y connectors.

I guess I could use the resistors with the Y connectors to slow the cpu cooler fans, but they increase before the others ai guess as they need to.
What I really need is more control over the roof fans to increase them to the same speed as the cooler fans. At the moment they are acting as a brake to the airflow. Fine on very slow speed or full speed, its the interim speed causing a slight turbulence sound. I.e. Coolers at 900rpm and the roof at 320 pr 350rpm.
Plus the cooler has 2 in line whereas the roof has on over the cooler and one partially straddling the cooler.

I may have to live with this if I cant put the roof fans on the cpu header as well.

Kinda spoils perfection, as the Noctuas at 350 rpm are virtually silent.

I do have to say Noctua are crazy, they have the best fans by a mile, yet the colour UGH! A dirty yellow and brown???
Give me black any day!