Also maybe there is room for a reset switch in front? Reset header disenfranchised?Maybe not worth the cost.
I asked for that before but it seems that everyone else just presses the power button for a few seconds to reset now.
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NCASE M1: a crowdfunded Mini-ITX case (updates in first post)
- Thread starter wahaha360
- Start date
I asked for that before but it seems that everyone else just presses the power button for a few seconds to reset now.
I had this problem using one of the Silverstone sleeved cable sets, so I used a different cable for the optical drive. Might be the issue you're seeing.
No room for it.Also maybe there is room for a reset switch in front? Reset header disenfranchised?
So the way it would be possible to have the option of moving the motherboard down is to cut away the part of the rear chassis between the I/O opening and first expansion slot, like so:
On the right is what it looks like with the motherboard moved down. You can see you're left with some awkward gaps above the I/O and part of the expansion slot. Without that bit of aluminum bridging the center with the left edge it's also going to make it somewhat less rigid than I'd like:
Do you guys think it's worth it?
Edit: that's assuming the standoffs could be made removable - not a given at this point.
AFD
2[H]4U
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Just insert the disc far enough, and it should finish feeding it. Few things to double-check.. make sure nothing is putting pressure on the eject button; remove the drive's faceplate and try feeding; make sure your internal power cord isn't putting too much pressure on the drive itself through the M1's cutout (mine cord was actually closing the drive's opening, so I routed the cable down further); double check your SATA power and data connections (and/or any micro adapter) to the drive; make sure your inserting your discs in the correct orientation (should still feed them with label in the wrong direction, though).
Otherwise, might be a DOA drive.. call the seller and return it.
A windowed panel could use a clear acrylic with ventilation holes drilled in it. Hell, the whole case would look sweet with all clear panels (think someone else mentioned this), cause a filled up naked M1 looks pretty damn good imo.
i forgot those types existed
I still don't see why slide-on panels would be so difficult to implement on the current M1.. use the same mounting areas as the pins/clips, but instead of pins have a small, narrow L or C-shaped pin tacked on (angling back toward the panel at the end for pressure.. tacking method same as for current pin, but slightly larger contact area) and instead of clips, just longer, thinner rectangular cut-outs (could even have a plastic insert or liner). Just need a small folded tab or two per panel that would screw into the back for safety (make the panels a tad longer, with excess cut away and fold/drill remaining tab). Everything else about the panels and M1 aesthetics would remain the same as they are now, other than the new rear tabs. Would almost entirely eliminate the issue of bent panels.
Dunno. Maybe it's just not possible, but this is what I'm thinking in my head..
And the expansion slots please. To hold a GPU with a metal waterblock those screw threads need to be reliable and that's the place I'd want to use extra force.
I guess not. That looks terrible.
Doing that will remove the ability to mount HDDs down there also make it a lot harder to do custom water loops as there will be no room i think its not worth it.
What was your ambient/room temp? My GPU sits around 55c and CPU around 65c that my normal gaming temps.
D
Deleted member 222586
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IMO, its time for a new thread. This one is too confusing, as we are mixing stuff from the original M1 with what seems to be another run (with a revised version).
I think this deserves a new thread, so that all the new info can go into the other thread, and use this for problems or stuff relating the current model.
I think this deserves a new thread, so that all the new info can go into the other thread, and use this for problems or stuff relating the current model.
Exactly (as I watch the number of pages concerning suggestions for the new revision increment) --
MikeTheTiger
Weaksauce
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Room temp is around 70F. Now that I think I have everything working well, the pump is making an annoying humming sound (I can hear it in the next room). Seems like I can't win!!
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You've missed the point. The idea is to allow both the current mounting, and a lower mounting position.
Then you're left with the alternate AC inlet hole uncovered.
None of these suggestions will work. I could go into detail why, but I won't. Just take my word for it.
Done.Exactly (as I watch the number of pages concerning suggestions for the new revision increment) --
Discussion of improvements for rev 2 of the M1 should be moved to this thread.
commander_
Limp Gawd
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MikeTheTiger
Weaksauce
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Unplugged the H220 pump from the fan splitter and plugged it into the mobo fan header. The fan splitter had it going at full speed. Now it's very quiet. Duh!!
AFD
2[H]4U
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Lol, I also considered badging up the interior.. nice build!
So, did you figure out what was causing your ODD feed issue??
commander_
Limp Gawd
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Yeah! Turns out I accidentally over-tightened a screw near the top of ODD, when I loosened it a bit, it started working
Ive been fowoling this thread for a while in hope to see the next ncase and get one but yesterday after searching for small cases in google ive found this thing...
http://jonsbo.com/en/products_23_1.html
Im not shore if it has been posted but it looks like you are inspiring other people.
If you people decide on making another ncase coud you please consider a micro atx form factor?Something maybe like the acubic g40 but with better airflow maybe?
http://jonsbo.com/en/products_23_1.html
Im not shore if it has been posted but it looks like you are inspiring other people.
If you people decide on making another ncase coud you please consider a micro atx form factor?Something maybe like the acubic g40 but with better airflow maybe?
Necere explained why he won't be making a mATX version in the first post of this thread.
But I wish there's a full tower version packed to the brim with HDD slots.
For this first edition case, most likely not :| unless you find someone selling theirs on eBay or a hardware forum.
You might have to wait for the next revision of the case that is being planned on. Necere and wahaha360 created a thread asking for recommendations for the next case. Sounds like it won't be a complete overhaul by any means, and will be very similar to the current one.
I am super close to getting Mac Pro as a "gaming"/workstation machine. Granted, that's crazy amount of money for what gaming performance it provides but theres nothing out there in the world that matches the performance/size/build quality.
This case was the first thing that made me go "hmm..."
Well, there's Digital Storm Bolt II to look at -- it's got a pretty big water cooler system. Could be quite nice indeed.
This case was the first thing that made me go "hmm..."
Well, there's Digital Storm Bolt II to look at -- it's got a pretty big water cooler system. Could be quite nice indeed.
ok, i got to stress test my system yesterday. i installed Windows 7, Intel ME, and Intel Chipset drivers, and AMD GPU drivers. then used Intel Extreme Tuning Utility and Intel Burn Test for the CPU and Unigine Heaven for the GPU.
on stock settings (CPU and GPU), the idle temps are 28C and 35C (if i remember correctly) for the CPU and GPU. with Intel XTU, my max CPU termp was 52C, the average was 49C-50C. with Intel Burn Test, for 10 rounds of Standard stress-level test, max CPU temp was 69C, and for 10 rounds of Very High stress-level test, the max temp was 71C. i also did about 20 minutes of Unigine Heaven and the max temp for the GPU was 78C.
this is with a Zalman LQ-310 AIO cooler and a Be Quiet! Silent Wings 2 fan. the Zalman fan can only be installed in push configuration. at first, i had my Be Quiet! fan as intake to bring fresh air into the case, and the CPU and GPU temps were about 3C-4C higher in general; i then changed it to exhaust, and both temps dropped. I can now feel that the holes at the top of the case and the 92mm fan slot both act as intakes. I need to order DEMCiflex filters; is there a filter for the 92mm fan slot at the back?
so, how are the temps? also, i am still undecided between Windows 7 and Windows 8.1 (which apparently makes BF4 run faster). which one do you guys suggest?
on stock settings (CPU and GPU), the idle temps are 28C and 35C (if i remember correctly) for the CPU and GPU. with Intel XTU, my max CPU termp was 52C, the average was 49C-50C. with Intel Burn Test, for 10 rounds of Standard stress-level test, max CPU temp was 69C, and for 10 rounds of Very High stress-level test, the max temp was 71C. i also did about 20 minutes of Unigine Heaven and the max temp for the GPU was 78C.
this is with a Zalman LQ-310 AIO cooler and a Be Quiet! Silent Wings 2 fan. the Zalman fan can only be installed in push configuration. at first, i had my Be Quiet! fan as intake to bring fresh air into the case, and the CPU and GPU temps were about 3C-4C higher in general; i then changed it to exhaust, and both temps dropped. I can now feel that the holes at the top of the case and the 92mm fan slot both act as intakes. I need to order DEMCiflex filters; is there a filter for the 92mm fan slot at the back?
so, how are the temps? also, i am still undecided between Windows 7 and Windows 8.1 (which apparently makes BF4 run faster). which one do you guys suggest?
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They aren't plastic clips but rubber and i'm not sure what exactly to call them.. washers perhaps?
is there a way to mount two 92mm fans at the bottom of the case? i'm trying to find quiet and slim fans to bring in some fresh air for the GPU, but all 120mm slim fans i've found are loud ( > 20db). only the 92mm Noctua NF-A9x14 fan has good sound characteristics, but as far as i can tell from the ncases.com information, we can only mount one 92mm fan at the bottom, right?
I have one 120mm and another 92mm from noctua but they are not slim. I just use fan speed from mobo to make them very quiet on idle. But from my tests even with both fans at 100% I just get around 2 degrees less on my GPU. So I don´t think it worth for me. I just still using it because I already bought it and to keep positive pressure inside.
I have attached 92mm with "Vibration Compensators". Bottom right: http://noctua.at/images/products/fullsize/noctua_nf_b9_3.jpg
Here inside the case: http://hardforum.com/showpost.php?p=1040498585&postcount=15
Depends on what you can tolerate as "quiet enough"
The Noctua A9x14 has a very quiet motor, no ticking at all! Aerodynamically its quiet too, but it certainly doesn't push much air at all, but when you are looking for more than just a little airflow, it becomes audible.
The Gelid slim 120mm fans are aerodynamically fairly acceptable, but it has a mildly clicky motor (coil switching sounds). Because its a 120mm, it will still push more air than the noctua for a given aerodynamic noise, but it will not deliver absolute silence when slowed down.
So if you want the quietest fan for a GIVEN minimum airflow, then the 120 will be the way to go, but if you want absolute SILENT IDLE performance, where you are not looking for any significant amount of airflow, i.e. you want absolute silence, then the noctua has the quieter motor.
If I have the Gelid slim fans on the bottom of the case, I can hear a mild ticking, but this is in a subjectively quiet environment. Overall, its a better than average fan in terms of noise, for a slim fan.
Note however that the reported ticking is not even comparable to the NB 80mm fan that people are using for the PSU. That NB ticks SOO loudly in comparison. And I would not say that mine was defective, its just a highly biased opinion of noise. I also consider a gentle typhoon audible for idle noise due to the ball bearing hiss.
So summary - choose a fan based on your goals
1) Absolute silence at idle - Nocta
2) Relative silence with some airflow under load conditions, and not fussed about idle noise - Gelid (if you must use a slim)
I have not had the experience of the Coolermaster slim, nor the Scythe slim. Also, don't trust dB ratings at all. They are all extremely subjective, and not measured in a comparable manner. You can only assess a fan for noise based on side by side comparisons, preferably to your ears, but at least use reviews as a guide. I have found that all reviews of the gelid slim fan I bought said that it was So silent they could not hear it at all, yet my first impressions were - Clicky motor! and so the 5 fans I just spent $100 on now sit in a box, among another $100s worth of unused fans from the search for the best fans…. Should try to sell them one day.
The Noctua A9x14 has a very quiet motor, no ticking at all! Aerodynamically its quiet too, but it certainly doesn't push much air at all, but when you are looking for more than just a little airflow, it becomes audible.
The Gelid slim 120mm fans are aerodynamically fairly acceptable, but it has a mildly clicky motor (coil switching sounds). Because its a 120mm, it will still push more air than the noctua for a given aerodynamic noise, but it will not deliver absolute silence when slowed down.
So if you want the quietest fan for a GIVEN minimum airflow, then the 120 will be the way to go, but if you want absolute SILENT IDLE performance, where you are not looking for any significant amount of airflow, i.e. you want absolute silence, then the noctua has the quieter motor.
If I have the Gelid slim fans on the bottom of the case, I can hear a mild ticking, but this is in a subjectively quiet environment. Overall, its a better than average fan in terms of noise, for a slim fan.
Note however that the reported ticking is not even comparable to the NB 80mm fan that people are using for the PSU. That NB ticks SOO loudly in comparison. And I would not say that mine was defective, its just a highly biased opinion of noise. I also consider a gentle typhoon audible for idle noise due to the ball bearing hiss.
So summary - choose a fan based on your goals
1) Absolute silence at idle - Nocta
2) Relative silence with some airflow under load conditions, and not fussed about idle noise - Gelid (if you must use a slim)
I have not had the experience of the Coolermaster slim, nor the Scythe slim. Also, don't trust dB ratings at all. They are all extremely subjective, and not measured in a comparable manner. You can only assess a fan for noise based on side by side comparisons, preferably to your ears, but at least use reviews as a guide. I have found that all reviews of the gelid slim fan I bought said that it was So silent they could not hear it at all, yet my first impressions were - Clicky motor! and so the 5 fans I just spent $100 on now sit in a box, among another $100s worth of unused fans from the search for the best fans…. Should try to sell them one day.
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There is a good description here:
http://hardforum.com/showpost.php?p=1040622397&postcount=10458
and picture here:
http://hardforum.com/showpost.php?p=1040624325&postcount=10463
thank you Proglin and okwchin.
i am aware of the airflow considerations of 92mm vs 120mm fans. what i have in mind, and i might be totally wrong, is to bring in a bit of fresh air from outside towards the GPU, and not to create a tornado vortex under the GPU (i am obviously exaggerating here). the GPU seems to be able to handle its cooling, however i realized that when i changed the 120mm side fan from intake to exhaust, the GPU temperature also dropped by 3C-4C while doing a Heaven benchmark, which points to the fact that the two exhaust side fans (AIO cooler fan and case fan) together create a flow pattern inside the case which takes some of the hot GPU air out as well. i am thinking that if i bring "some" fresh air from under the case, that will also push the hot GPU air up towards the top of the case to be exhausted by the big 120mm fans, so the GPU will get more breathing room. again, i might be wrong.
i want a slim fan because i don't want the fan to "touch" the GPU and i want it to not have a very strong airflow to cause GPU fans to stall for air. basically, i want the air flow under the GPU to stabilize before being taken in by the GPU fans to cool the core.
as for which fans, i only researched Noctua A9x14 and Scythe Slim fans. thanks for pointing out the other options. but i think in terms of acoustics and air flow, the Noctua would be a better choice, although it's 2mm taller than the Scythe slim fan (i don't think that matters). unfortunately, i don't think i can mount two 92mm fans at the bottom.
and thanks for the warning about buying fans; i was stupid enough to buy two 120mm Be Quiet! Silent Wings 2 fans, thinking that i'd use both in the case; given their price in Canada (and my choice of online retailer), i basically wasted my cash as one of them is still in a sealed box! maybe i can install the unused one at the bottom to test my theory...
I agree that your change with the side fans from intake to exhaust has changed the airflow pattern.
As an intake, you are creating a positive pressure system, which would be pushing air out of all the other vents in the case, at a slow rate, but out the case none the less. For the GPU, with its bottom placement and proximity to the bottom openings, this means the hot air that comes out of the GPU is pushed away from the intake side fans, and toward the bottom openings. The GPU cooling fan intake is closest to the bottom panel, and thus increases the percentage of hot air recirculation.
Changing it to an exhaust creates a negative pressure system, and this means air is entering the case at all case openings, including the bottom. So rather than having the hot air pushed below the GPU, cooler air is entering the bottom and displacing the exhaust air upwards away from the GPU. This is therefore reducing the percentage of hot air recirculation.
you will be defining your goals, and the order of importance. The following is what I follow for my case.
1) GPU cooling
2) CPU cooling
3) Ambient Case Temperature --> temperatures of all other components.
To minimise GPU temperature first, it must receive the coolest air supply, and a way for the exhaust air to be removed and not recirculated back to the GPU. Giving it air from the outside of the case is a priority, and thus a negative pressure as you have created with the side fans, or a positive pressure with bottom fans to improve dust control.
CPU side panel fan as intake helps control dust again, but the positive pressure generated by this fan will create a back pressure against the bottom fans because we have a increasingly positive pressure differential. What this pressure differential causes is a drop in airflow, and the weaker the static pressure the fans, the greater the effect. So a low RPM slim fan is about as bad as it gets, and the reduction in airflow will be notable.
Aero
Speaking of aerodynamics, there is something that has been bothering me with the discussions about fans.
There has been many discussions about stalling fans, but the use of the term stalling seems incorrect.
Heres a few paragraphs about - The aerodynamics of stalling, and its significance to computer fans - understanding how fans work.
A fan blade
With the context of a fan blade, there is a fan blade passing through the air. The fan blade is angled with respect to the air, called the Angle of attack, or incidence.
Lets give the blade a 5 degree angle of attack. This angle causes air to be pushed, lets say for this discussion, downward. Air below the blade is pushed down when it hits the bottom surface of the blade, simple enough, but air above the fan blade follows the top surface of the blade and is also pushed/sucked downward as the blade passes. This is possible because of the negative pressure behind the blade… So air either side of the blade is redirected downward. The point here is that the angle of the blade is gentle enough for the air above the blade to maintain smooth flow over the top of the blade.
More angle of attack means more air?
As we increase this angle of attack, toward 15-20 degrees say, we can imagine that the air would be pushed down faster, but theres a limit to how much angle we can use. If we increase the angle too much, the air that is on top, or behind the blade does not have sufficient negative pressure to be sucked/pushed down, and no longer follows the top surface of the blade. It ends up breaking away from the top surface of the blade, twirling around and not going anywhere, wasting energy and creating noise. This is known as a loss of laminar flow, and is the definition of stalling.
A fan will still push air when stalled, but it is not as efficient, as the air behind the blade is not propelled in a helpful direction, and it creates more noise instead.
Optimal angle?
How do we prevent stalling? We need to ensure the fan blade has an appropriate angle of attack, or pitch of the blade. An ideal angle of attack is close to the maximum angle before stalling, lets say 15 degrees to the air that its passing.
Lets go back and recall that the angle of attack of the blade is measured against the air as it passes the blade. A fan is designed to push air, but once the air is moving, there is an effective reduction of the angle of attack of the blades as the air itself is moving through the fan under its own accord.
We need to increase the pitch of the blades as the speed of the air increases, to ensure that the fan blade is still seeing a positive angle of attack, to ensure that it is still contributing to accelerating the air flow.
More Pitch
Having more pitch means a fan will be able to push air well in situations that allow a high rate of airflow, but once you slow that airflow down with things that block the air from moving freely, such as radiators, filters, small case vents, back pressure, then you can see that the effective air speed will fall, and the effective angle of attack of the blades increases, causing it to go beyond 15-20 degrees and stalling the blade. So this fan will push lots of air very fast in an open environment, but once you load it up with restrictions, the fan falters very quickly. Sort of like driving a car in 5th gear, giving you lots of speed, but if you are towing a trailer, and never get to cruising speed, you will struggle. Good to win a race, but give you a caravan to tow, and your not going anywhere.
This type of fan can often be identified by features such as - high angle of attack, usually is visible as, multiple thin blades, and you can effectively see through the fan when viewed face on. They are generally described as Case fans, and would have high CFM ratings (for a given RPM). The Corsair AF120 series fans are a great example.
Less Pitch
Having less pitch means that the fan will start to push the air well as its nearer an optimal angle of attack initially, but once the speed of the air flow rises a little, the effective angle of attack falls quickly, and the blades are not really contributing much to accelerating the air anymore. This fan will not push air very fast, but if you restrict the airflow, and slow it down, the fan will be back at operating at its comfortable angle of attack, and will continue to be able to effectively push air through high resistance.
This is like driving in first or second gear, a setup which lacks top speed, but has the pulling/pushing power to tow your caravan. In a race where your towing a caravan, this is certainly the setup that wins.
This type of fan is often identified by features such as, low angle of attack, usually visible as wide blades, and smaller numbers of blades, with a difficulty in seeing through the fan when viewed face on. They are generally described as high pressure fans, and generally do not have impressive CFM ratings (for a given RPM). The Corsair SP120 fans are a great example of this.
So which is better? and why do each exist?
Each fan has a place, and if any of the above made sense, then the choice of fan will be somewhat clearer! In open cases with lots of vents and places for air to go, a case fan is appropriate, but highly restrictive applications such as small cases, cases without many vents, or more importantly, an imbalanced number of intake/outlet fans/vents then a high pressure fan becomes favourable.
The NCase M1 can be considered in need of a higher pressure fan, especially when 4 fans are installed, with all 4 acting as intakes. You are creating a high pressure internally, with less surface area available for the air to leave the case. Then we add Demcifilters, and a later of dust…
There are Many many more factors at play, but at least thats a rough outline of the basics of fans. For a lot of us, the choice of a fan is probably more down to what is available at your supplier, the price, and if you like the colour of the fan, but at least I hope that this helps a few people understand what types of fans exist, and what it really means for a fan to be stalled.
Fans in Series
Which then brings us back to another point - Why does putting two fans in series, not double the airflow. I would imagine that one could now answer that question - Effective angle of attack.
The first fan will accelerate the air to a certain speed. If an identical fan is placed behind it, it will be fed air that is already moving, and the effective angle of attack of the second fans blades will be much closer to zero, and therefore it will contribute very little to accelerating the air.
What is required of the second fan is one with a much blade pitch to increase the effective angle of attack so that it too could contribute to increasing the air flow.
If you were to install a fan in the reverse order, with the front one with more pitch, and the rear one with less pitch, the front will will push air, but because the rear fan is a low pitch, it could have an effectively negative angle of attack to the incoming air, and thus actually Block the air coming through! This is one way that having two fans in series can reduce the output of a single fan.
Different RPMs
Another concern many people have expressed is a concern for different RPM fans and sizes in close proximity.
Having fans of differing RPMs is also a concern for exact fan efficiency, but practically, you are not losing airflow over having a single fan, especially in the context of real world applications. There is concern that there is buffeting between two fans because the air is accelerated by the blade of the first fan and then slows down until the next blade passes. What this does to the second fan, is it causes the effective angle of attack of the air passing the blades of the second fan to vary up and down with each passing of the blades of the first fan.
Yes, the second fan is not pushing at as effectively as it could be, but the point here that is being missed, is that the first fan is already pushing air Through the second fan. Compared to simply having the second fan alone, there is already a NET GAIN in airflow. The second fan is just not accelerating the air as efficiently, but we are talking about accelerating are that is already moving.
What would be a problem is if the motor hub of the first fan was so close to the second fan, that you were physically blocking the second fan, or if the fan you added is blowing air elsewhere too, and changing the airflow pattern. These are far more significant issues…
As an intake, you are creating a positive pressure system, which would be pushing air out of all the other vents in the case, at a slow rate, but out the case none the less. For the GPU, with its bottom placement and proximity to the bottom openings, this means the hot air that comes out of the GPU is pushed away from the intake side fans, and toward the bottom openings. The GPU cooling fan intake is closest to the bottom panel, and thus increases the percentage of hot air recirculation.
Changing it to an exhaust creates a negative pressure system, and this means air is entering the case at all case openings, including the bottom. So rather than having the hot air pushed below the GPU, cooler air is entering the bottom and displacing the exhaust air upwards away from the GPU. This is therefore reducing the percentage of hot air recirculation.
you will be defining your goals, and the order of importance. The following is what I follow for my case.
1) GPU cooling
2) CPU cooling
3) Ambient Case Temperature --> temperatures of all other components.
To minimise GPU temperature first, it must receive the coolest air supply, and a way for the exhaust air to be removed and not recirculated back to the GPU. Giving it air from the outside of the case is a priority, and thus a negative pressure as you have created with the side fans, or a positive pressure with bottom fans to improve dust control.
CPU side panel fan as intake helps control dust again, but the positive pressure generated by this fan will create a back pressure against the bottom fans because we have a increasingly positive pressure differential. What this pressure differential causes is a drop in airflow, and the weaker the static pressure the fans, the greater the effect. So a low RPM slim fan is about as bad as it gets, and the reduction in airflow will be notable.
Aero
Speaking of aerodynamics, there is something that has been bothering me with the discussions about fans.
There has been many discussions about stalling fans, but the use of the term stalling seems incorrect.
Heres a few paragraphs about - The aerodynamics of stalling, and its significance to computer fans - understanding how fans work.
A fan blade
With the context of a fan blade, there is a fan blade passing through the air. The fan blade is angled with respect to the air, called the Angle of attack, or incidence.
Lets give the blade a 5 degree angle of attack. This angle causes air to be pushed, lets say for this discussion, downward. Air below the blade is pushed down when it hits the bottom surface of the blade, simple enough, but air above the fan blade follows the top surface of the blade and is also pushed/sucked downward as the blade passes. This is possible because of the negative pressure behind the blade… So air either side of the blade is redirected downward. The point here is that the angle of the blade is gentle enough for the air above the blade to maintain smooth flow over the top of the blade.
More angle of attack means more air?
As we increase this angle of attack, toward 15-20 degrees say, we can imagine that the air would be pushed down faster, but theres a limit to how much angle we can use. If we increase the angle too much, the air that is on top, or behind the blade does not have sufficient negative pressure to be sucked/pushed down, and no longer follows the top surface of the blade. It ends up breaking away from the top surface of the blade, twirling around and not going anywhere, wasting energy and creating noise. This is known as a loss of laminar flow, and is the definition of stalling.
A fan will still push air when stalled, but it is not as efficient, as the air behind the blade is not propelled in a helpful direction, and it creates more noise instead.
Optimal angle?
How do we prevent stalling? We need to ensure the fan blade has an appropriate angle of attack, or pitch of the blade. An ideal angle of attack is close to the maximum angle before stalling, lets say 15 degrees to the air that its passing.
Lets go back and recall that the angle of attack of the blade is measured against the air as it passes the blade. A fan is designed to push air, but once the air is moving, there is an effective reduction of the angle of attack of the blades as the air itself is moving through the fan under its own accord.
We need to increase the pitch of the blades as the speed of the air increases, to ensure that the fan blade is still seeing a positive angle of attack, to ensure that it is still contributing to accelerating the air flow.
More Pitch
Having more pitch means a fan will be able to push air well in situations that allow a high rate of airflow, but once you slow that airflow down with things that block the air from moving freely, such as radiators, filters, small case vents, back pressure, then you can see that the effective air speed will fall, and the effective angle of attack of the blades increases, causing it to go beyond 15-20 degrees and stalling the blade. So this fan will push lots of air very fast in an open environment, but once you load it up with restrictions, the fan falters very quickly. Sort of like driving a car in 5th gear, giving you lots of speed, but if you are towing a trailer, and never get to cruising speed, you will struggle. Good to win a race, but give you a caravan to tow, and your not going anywhere.
This type of fan can often be identified by features such as - high angle of attack, usually is visible as, multiple thin blades, and you can effectively see through the fan when viewed face on. They are generally described as Case fans, and would have high CFM ratings (for a given RPM). The Corsair AF120 series fans are a great example.
Less Pitch
Having less pitch means that the fan will start to push the air well as its nearer an optimal angle of attack initially, but once the speed of the air flow rises a little, the effective angle of attack falls quickly, and the blades are not really contributing much to accelerating the air anymore. This fan will not push air very fast, but if you restrict the airflow, and slow it down, the fan will be back at operating at its comfortable angle of attack, and will continue to be able to effectively push air through high resistance.
This is like driving in first or second gear, a setup which lacks top speed, but has the pulling/pushing power to tow your caravan. In a race where your towing a caravan, this is certainly the setup that wins.
This type of fan is often identified by features such as, low angle of attack, usually visible as wide blades, and smaller numbers of blades, with a difficulty in seeing through the fan when viewed face on. They are generally described as high pressure fans, and generally do not have impressive CFM ratings (for a given RPM). The Corsair SP120 fans are a great example of this.
So which is better? and why do each exist?
Each fan has a place, and if any of the above made sense, then the choice of fan will be somewhat clearer! In open cases with lots of vents and places for air to go, a case fan is appropriate, but highly restrictive applications such as small cases, cases without many vents, or more importantly, an imbalanced number of intake/outlet fans/vents then a high pressure fan becomes favourable.
The NCase M1 can be considered in need of a higher pressure fan, especially when 4 fans are installed, with all 4 acting as intakes. You are creating a high pressure internally, with less surface area available for the air to leave the case. Then we add Demcifilters, and a later of dust…
There are Many many more factors at play, but at least thats a rough outline of the basics of fans. For a lot of us, the choice of a fan is probably more down to what is available at your supplier, the price, and if you like the colour of the fan, but at least I hope that this helps a few people understand what types of fans exist, and what it really means for a fan to be stalled.
Fans in Series
Which then brings us back to another point - Why does putting two fans in series, not double the airflow. I would imagine that one could now answer that question - Effective angle of attack.
The first fan will accelerate the air to a certain speed. If an identical fan is placed behind it, it will be fed air that is already moving, and the effective angle of attack of the second fans blades will be much closer to zero, and therefore it will contribute very little to accelerating the air.
What is required of the second fan is one with a much blade pitch to increase the effective angle of attack so that it too could contribute to increasing the air flow.
If you were to install a fan in the reverse order, with the front one with more pitch, and the rear one with less pitch, the front will will push air, but because the rear fan is a low pitch, it could have an effectively negative angle of attack to the incoming air, and thus actually Block the air coming through! This is one way that having two fans in series can reduce the output of a single fan.
Different RPMs
Another concern many people have expressed is a concern for different RPM fans and sizes in close proximity.
Having fans of differing RPMs is also a concern for exact fan efficiency, but practically, you are not losing airflow over having a single fan, especially in the context of real world applications. There is concern that there is buffeting between two fans because the air is accelerated by the blade of the first fan and then slows down until the next blade passes. What this does to the second fan, is it causes the effective angle of attack of the air passing the blades of the second fan to vary up and down with each passing of the blades of the first fan.
Yes, the second fan is not pushing at as effectively as it could be, but the point here that is being missed, is that the first fan is already pushing air Through the second fan. Compared to simply having the second fan alone, there is already a NET GAIN in airflow. The second fan is just not accelerating the air as efficiently, but we are talking about accelerating are that is already moving.
What would be a problem is if the motor hub of the first fan was so close to the second fan, that you were physically blocking the second fan, or if the fan you added is blowing air elsewhere too, and changing the airflow pattern. These are far more significant issues…
yimingwuzere
Gawd
- Joined
- Sep 13, 2009
- Messages
- 618
For those guys who bought the Ncase reservoirs from FrozenQ... any idea how long it'll be at "Awaiting Fulfillment" before they ship one out?
Here is my timeline (keep in mind this was during the holiday rush, and for the frosted acrylic instead of the basic black):
11/26/13 - Order placed
12/17/13 - Creating Product
1/16/14 - Shipped
1/21/14 - Delivered
I did not get any other status updates via email
11/26/13 - Order placed
12/17/13 - Creating Product
1/16/14 - Shipped
1/21/14 - Delivered
I did not get any other status updates via email