Question Fan type question...

Jan 23, 2021
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I'm trying to find a particular type of fan. I'm sure it exists but don't know the technical name for it. Basically, I need a fan, but rather than the chassis being closed off on the sides, I would like an open fan design so that the air can pass out of the sides of the fan rather than top and bottom. Obviously the fan needs some kind of chassis to hold it together, but I'm looking for one with big gaps in the sides. Does anyone know what are these called? Thanks
 

Paperdoc

Glorious
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Yeah. Common computer case fans are called Axial because the air flow is parallel to the axle of the fan motor. A Radial fan blows air out to the side, tangentially from the axle, but not on all sides. It normally blows out through a side-facing chute that is part of the shroud around the fan drum. Intake is from an opening in the shroud on the opposite side from the motor.

If you actually want a fan that blows air out of the SIDES but all around, I don't think they make those. Yoiu might create one by using an axial fan and mounting in front of it some kind of curved cone to re-direct air to all sides.
 
Jan 23, 2021
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@Grobe @Paperdoc

It's kind of like a radial fan, but without the chute on it. I was looking for something like a standard axle fan chassis (square), but with no sides on it, and the radial (water wheel) style fan in it. Similar to this with a minimal frame on it (http://ak1.ostkcdn.com/images/products/9096804/Corsair-Black-200mm-Case-Fan-2dbaf07f-2795-40fe-b2f9-70e3ef035fad.jpg)
but with the radial (waterwheel) style fan in it, similar to certain graphics card fans like this (https://www.moddiy.com/product_images/t/033/T1quTyXbBjXXbkuMgU_014611__51736_zoom.jpg)

Basically, I bought a 1u server to use as a workstation, and it's a bit loud (6 x 40mm fans whining away), so I'm wanting to stick a cooler inbetween the 2 cpu heatsinks, and blow air sideways directly onto them so that I can then disconnect the 40mm fans. The gap in between the heatsinks is almost exacly 120mm, so I initially wanted a 120mm fan, but as I'm having trouble finding what I need, I'd settle for something slightly smaller.

That's a good idea about mounting an axial fan on a cone, but I'm limited to 1u height...

Here is a pic of the board with the cpu heatsinks https://i.ebayimg.com/00/s/MTYwMFgxNjAw/z/yZQAAOSw93dfFg2m/$_57.jpg

What I'm trying to do is lay the fan on top of the ram slots in the middle, and have the air blow sideways when the case lid is on.

I have considered replacing the cpu heatsinks with active heatsinks like the akasa one here http://www.akasa.co.uk/update.php?tpl=product/cpu.product.tpl&no=181&type=CPU coolers&type_sub=Low Profile&model=AK-CC6503BP01

As I'm going to have to purchase 2 of them though, it's going to be expensive (nearly half as much as I paid for the actual server).
 
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Paperdoc

Glorious
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I suspect strongly that the radial side-discharge fan type you show from a graphics card actually works becsue the metal shroud around it and / or other card components function as air "chutes" to direct the air in the right areas. Other than that I have not seen any fan like you are looking for. The Akasa fan concept certainly is viable - it's just designed for air flow over the hot device to be by suction, rather than output pressure. I do appreciate the cost factor, though, probably because this is a very small-volume market item. Just how much space is there above each CPU heatsink before hitting the outer cover? I'm thinking there are pretty"standard" fans at reasonable prices that are only 15 mm thick, instead of the standard 25 mm thickness. IF you have that much space, you could mount one over each heatsink, and custom-cut holes in the cover over them to admit air, then include a foam dust filter outside the case top. Another option I used for a small tight case and a new fans: cut those case-top holes over each heatsink, then mount the normal fans OUTSIDE the case with their own dust filters on their intakes. This might not work if your unit actually were in a rack with other units close by, but might if you have space over the top.
 
Jan 23, 2021
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@Paperdoc Unfortunately there isn't any space above the CPU heat sinks. Probably a few mm at most, so mounting a fan on top of it isn't possible. I did consider mounting the fan outside of the case, but this means cutting holes in the case cover, which I was saving as a last option. I have decided at this stage to buy a couple of lower rpm fans to replace the (19000) rpm fans which are currently in there. I'll see how they perform, and may buy more of them and/or mount some fans outside of the case if needed. Thanks very much for your input thus far. Much appreciated.
 
@Paperdoc Unfortunately there isn't any space above the CPU heat sinks. Probably a few mm at most, so mounting a fan on top of it isn't possible. I did consider mounting the fan outside of the case, but this means cutting holes in the case cover, which I was saving as a last option. I have decided at this stage to buy a couple of lower rpm fans to replace the (19000) rpm fans which are currently in there. I'll see how they perform, and may buy more of them and/or mount some fans outside of the case if needed. Thanks very much for your input thus far. Much appreciated.
Take a look at these fans for GPUs https://www.amazon.com/Graphics-Card-Fans/b?ie=UTF8&node=3015421011 they don't have a shroud.
 

Paperdoc

Glorious
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That first fan pair might be adaptable. Of course you can only use one, but that should not be a big issue. The issues that do come to mind to be solved (not too hard):
  1. Find pinout labels for the cable on the fan pair. "4-pin" does not tell you, although they MAY use a similar arrangement for case fans. I note these are specified for particular MSI video cards.
  2. How to mount / suspend? Location presumably over the RAM slots between the two CPU's. Are those slots empty? Is there space for the fan thickness PLUS some gap for the fan blades to intake air? Can you drill holes in the 1U top for bolts through the fan mounting holes?
  3. Where to plug in the fan? Depends what the mobo has, and what the pinout details are on the fan cable, regarding both power and speed control if any.
  4. Can you rig some kind of air-direcrting "fence" on two sides of the fan so that air is directed only towards the heatsinks on either side?
  5. Do those heatinks actually have fins in the correct direction for air to flow between - that is, from fan location to outer edges? If the heatsink is a solid block with only ridges along the top surface (shown from bottom to top in the photo), then air flow is only across a set of ripples, and not through a set of fins.
 
Jan 23, 2021
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Thanks @Paperdoc . Yes the ram slots are empty. I don't have much room to play with. Realistically, about an inch from the top of the ram slots, to the top of the case. I'm tempted to just power it via a spare VGA power plug (which is the same as a 4 pin 12v connector, but measures 24v) and have it on full blast. That's a good idea about the air directing thing. I'll probably land up doing that. Yes, unfortunately, the heat sinks are positioned towards the front of the case where the 40mm fans are, and they blow directly into the fins via a shroud, so the fan in between the heat sinks will be blowing on a solid piece of heat sink, rather than through fins. Still waiting for my other fans to arrive, but I'd very much like to fit a fan between the heat sinks anyway. Yes, hopefully if I can just drill a few holes in the top of the case, I can suspend the fan from inside. The ideal fan thickness would probably be about 10-15mm thick, as this would allow just a bit of room between the fan and ram slots, and also the fan and the top of the case.
 
Jan 23, 2021
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@Paperdoc The fans arrived but although they were quiet, they were pretty wimpy in performance, so I ordered a couple of high airflow 92mm fans, along with a fan controller, and have decided to just drill a couple of holes in the top of the case, and mount them on the outside directly over the cpu heatsinks. I have done a test run before mounting them properly, and the temps a pretty cool, even under load. Thanks for your input on this thread. You too @Grobe and @CountMike . Much appreciated :)
 
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