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Noctua Unveils The NH-D15, The Successor To The NH-D14

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BonzaiDuck

Lifer
Jun 30, 2004
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Shoots straight into the big fan up top on the 1200.
Actually, I'm going to offer a reply to this, also. I'd seen your configuration before. And if you want to run the top fans as an exhaust, it also has promise. But you could reduce the number of fans (starting with a couple Noctuas or even all), keep the same cooler orientation (or not!), and improve the temperatures you get with the D14.

You might not want to trouble yourself with it. Just thought I'd tell you, though . . .
 

BonzaiDuck

Lifer
Jun 30, 2004
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By the way -- and I apologize for some three successive posts.

One of these reviews -- Overclock3D -- is worth inspecting in comparison to a Frosty Tech comparison I've referred to in earlier posts: they both include the CM Nepton 280L in the comparisons -- an AiO water-cooler that is quite favorable for such products.

Last time I looked, the D14 came to within some 11 to 14C of the Nepton on an overclocked testbed.

Here, the D15 shows to be within 3C of the Nepton result -- for an i7-3960X clocked to 4.4 Ghz and VCORE ~= 1.35V.

I'm going to look at this and some other reviews some more, but if I can squeeze another 5 to 10C out of the cooler by fan replacement, ducting and other minor little adjustments, I might just spring for one. I don't NEED it! But I just might WANT it enough to shell out the ducats and reallocate my D14 to another application.

Since I CAN squeeze out the 5 to 10C on my D14, I think this could be a good gamble. Have to wait and see.
 

DrMrLordX

Lifer
Apr 27, 2000
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Well, you did say psu. Be nice to see what Noctua could bring to the table in that segment.

Anyway, not too many companies selling fanless hsf's anymore. Prolimatech still does but TR only has HR-22 at the moment (which sort of makes sense for a passive-type hsf). Simple fact is most popular coolers, either air or aio, come with fans.
Huh! I must have been in a haze. Oh well! Sorry about the typo.

Yeah fanless isn't popular anymore. Oh well. Turns out even lots of enthusiasts can't stand computers that sound like vacuum cleaners, or model airplane landing strips . . .

This is something that i'm concerned about. Would be a major dealbreaker for me and I'd guess for many potential users. I'm going to google around a bit and see if I can find a compatibility list or something.

EDIT: Found it. http://www.noctua.at/main.php?show=compatibility_gen&products_id=34&lng=en#LGA2011_Gigabyte

Worth nothing that the review located here http://www.overclock3d.net/reviews/cases_cooling/noctua_nh-d15_review/6 (linked above by gradoman) uses a motherboard that is not fully compatible with the N15.
Hmm, good find there. I've managed to live peaceably with my D14 by using only two RAM DIMM slots, and fortunately, my board just happened to run dual channel configs with DIMMs populated next to one another rather than in an offset configuration. Don't remember if I got lucky or planned it that way. Probably just luck.

If it had blocked the first PCIe slot on my board, I definitely would have needed to go with a different cooler.

I can say something about that -- the size maybe interfering with a gfx-card slot. I'd rather doubt this is going to happen on various mainstream ATX motherboards, especially with a Noctua product. But if it does, it may not be sufficient reason to choose some other cooler -- if the D15 fills your bill and floats your boat.
This is (sort of) one of the reasons why I'm so interested in APU products. Being able to cool the CPU and GPU with one monolithic beast (like the D14 or D15) is pretty slick. The fact that you no longer have to worry about blocking your video card might be an added bonus for the D15.

On the other hand, the D15 is more expensive than many APUs out there . . .

On the matter of "100 CFM" fan choices -- you got that right!! I'm repeating myself again: Every so often I run IBT or LinX under my current fan-profile so I can "pinch" myself at how quiet my Gentle Typhoon AP-30 spins to within 300 RPM of its 4,250 top-end, and still seems relatively quiet except for the air-turbulence -- which also seems like almost nothing . . . At that speed, we're not just talking about your 100 CFM, but more like 120 to 130 CFM.
Sometimes I think that I should have gone with one of those ~200 CFM Deltas back when I got my last set of fans. Then I remember that the dB scale is logarithmic and think otherwise. My hearing is already shot, but that doesn't mean I have to torture everyone else.

I'm beginning to wonder -- with that sort of airflow -- if it actually reduces kruft build-up by blowing out all the kruft!
It does. You get different kinds of dust in high airflow situations . . . mostly fine powder. No dust bunnies, hair, or other chunky stuff.
 
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BonzaiDuck

Lifer
Jun 30, 2004
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. . .

Sometimes I think that I should have gone with one of those ~200 CFM Deltas back when I got my last set of fans. Then I remember that the dB scale is logarithmic and think otherwise. My hearing is already shot, but that doesn't mean I have to torture everyone else.

It does. You get different kinds of dust in high airflow situations . . . mostly fine powder. No dust bunnies, hair, or other chunky stuff.
It was my "low-tech" acoustic-mod project, posted in a thread about the "Gentle Typhoon." I wouldn't have the NH-D14 in an over-clocked system without a decent attempt to duct the air and reduce the number of fans while actually increasing CFM. First, I obsessed over getting total fan control for all fans within the case from the motherboard without overloading it. Then -- playing with the fan curves in the AI Suite software that gets a lot of criticism -- but it works pretty well.

I layered the duct-box porting the D14 to the AP-30 rear exhaust fan with Spire acoustic foam-rubber -- enough layers of the stuff that there's no more space between the duct box and the left side-panel. And I laid down the foam padding inside the duct as well as putting it in layers on the exterior.

So I appreciate your appraisal of the "decibel scale" as logarithmic. And I'm picking fans like the AP-30 which are in the 50 dBA range of ratings. But with the "acoustic mod" -- most of the sound that remains is a gentle "whoosh" like your air-conditioning wall-duct. I think I've adequately suppressed the noise -- logarithmic, linear or otherwise. At temperatures below 60C, the fan is essentially noiseless at 2,800 RPM -- maybe a little more or less. Frankly, 3,950 RPM is about 700 RPM beyond maximum cooling effect -- anything above 3,200 RPM won't much matter.
 

DrMrLordX

Lifer
Apr 27, 2000
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Looking at the d15 a little bit more, I have to ask: is this thing better off with 120mm or 140mm fans? It looks like the d15 is wider than the d14, but not taller.
 

Essence_of_War

Platinum Member
Feb 21, 2013
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I think it comes with NF-A15's which are top-notch 140mm fans, I probably wouldn't go smaller.
 

DrMrLordX

Lifer
Apr 27, 2000
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I think it comes with NF-A15's which are top-notch 140mm fans, I probably wouldn't go smaller.
Hmm . . . 73 dBA. Who needs hearing anyway?

Actually, wait. Does the d15 support fans with 120mm mount holes, 140mm mount holes, or both? I'm pretty sure those A15s have 120mm mount holes. Yep, they do.
 

BonzaiDuck

Lifer
Jun 30, 2004
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Hmm . . . 73 dBA. Who needs hearing anyway?

Actually, wait. Does the d15 support fans with 120mm mount holes, 140mm mount holes, or both? I'm pretty sure those A15s have 120mm mount holes. Yep, they do.
The so-called "round" 140mm fans are indeed fitted with holes for your standard square 120mm fan.

Whether these new Noctua fans are better than those shipped with the D14, I cannot judge. I can only say that replacing the Noctua (a) 120mm and (b) 140mm "round" fan with a single 140mm "round" Akasa Viper improved cooling on my system by up to 5C degrees. When I made that observation, I was pretty sure of ambient temperatures and other control factors, but it was only one observation of comparison. Even so, I was satisfied with cooling improvement, reduced weight on the D14, and especially - the lack of noise at the Akasa's top-end. It doesn't mean that it is completely "noiseless:" it means that it is quiet!

Whether 120mm or 140mm, it is not the only factor which determines cooling effectiveness. I'd shown that ducting the rear of these double-tower coolers (with a 140 round fan between the towers) draws air through three sides of both the towers. This can reduce the significance of "less coverage" with a 120mm fan.

But I'd recommend 140mm fans over 120's: to reduce the noise, to elevate the airflow, and even provide a "ducting" effect of the fan's own fan-shroud.

On the matter of fans with "73 dBA" rating: Sounds like the old Vantec Tornado! But with such a noise level, the probability of any modified usage for such a fan decreases.

I WILL, however, continue to tout the success of my acoustic mod to a Gentle Typhoon AP-30 in my case's 120mm exhaust -- together with ducting it to the rear of the D14.
 
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BonzaiDuck

Lifer
Jun 30, 2004
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This review shows the NH-D15 beating the TC14PE and NH-D14 by 2 Celsius and beating the H100i with 3 Celsius difference.

http://www.relaxedtech.com/reviews/noctua/nh-d15/1
There was another review I've mentioned more than once recently at Frosty Tech. It just seems that the spread between the D14 and the Corsair H100i was more pronounced and in Corsair's favor --- opposite this review. It wasn't very much, though. Maybe my remembrance of it is wrong. . .

So what could I do with a D15 guaranteeing 3. . 4C degrees better than the predecessor? What would it mean for an acoustically-deadened Gentle Typhoon AP-30 to suck air through that puppy at ~4,000 RPM, with a wider fine-array and ducting to the rear tower?

I could pay to find out. But if I have to pay, what's it worth to me?
 

BonzaiDuck

Lifer
Jun 30, 2004
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I had totally forgotten how large those air sinks are...looks cool!
I won't tell MongGrel what he should do with his system or how to do it. But his "configuration" points up options in my own "bag of tricks."

Generally, I've found that it's possible to reduce the number of fans overall, that case-makers design fan-vents as "options" for a range of configurations, and that I might find it useful to block off vents I don't need.

The top vent provides a good exhaust option -- no less "in addition to" the rear exhaust. I can only guess from the photo that MonGrel is using the rear fan ports and the top as exhaust.

I had recently thought to further increase airflow and "fin coverage" by creating two ducts at right angles: One for the rear fan ports, and another for the top vent. With the proper duct design, there would be no need for ANY fans on the D14 itself. All intake to the fins would enter through two adjacent sides -- and there would be special ducting features for the space between the towers. This latter would be rather simple: an obstructive piece of foam board inserted between the towers.

We know that airflow only "goes so far." Such a project wouldn't "hurt," but the payoff might not seem worth the trouble. Still. . . . who knows? Has anyone tried it?
 

4960X

Member
Jan 26, 2014
74
1
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Looking at the d15 a little bit more, I have to ask: is this thing better off with 120mm or 140mm fans? It looks like the d15 is wider than the d14, but not taller.
I remember reading it somewhere in this review that the NH-D15 is 10 mm taller than the NH-D14.
http://www.relaxedtech.com/reviews/noctua/nh-d15/1

There was another review I've mentioned more than once recently at Frosty Tech. It just seems that the spread between the D14 and the Corsair H100i was more pronounced and in Corsair's favor --- opposite this review. It wasn't very much, though. Maybe my remembrance of it is wrong. . .

So what could I do with a D15 guaranteeing 3. . 4C degrees better than the predecessor? What would it mean for an acoustically-deadened Gentle Typhoon AP-30 to suck air through that puppy at ~4,000 RPM, with a wider fine-array and ducting to the rear tower?

I could pay to find out. But if I have to pay, what's it worth to me?
Honestly, I think you could get more performance out of the D15 than what these reviewers are getting. The NF-A15 PWM fans that ship with the D15 seem to be much better at moving air than the fans that ship with the D14. But those AP-30 fans would be even better in my opinion. I think I'm going to pull the trigger on the D15.
 

BonzaiDuck

Lifer
Jun 30, 2004
14,920
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I remember reading it somewhere in this review that the NH-D15 is 10 mm taller than the NH-D14.
http://www.relaxedtech.com/reviews/noctua/nh-d15/1


Honestly, I think you could get more performance out of the D15 than what these reviewers are getting. The NF-A15 PWM fans that ship with the D15 seem to be much better at moving air than the fans that ship with the D14. But those AP-30 fans would be even better in my opinion. I think I'm going to pull the trigger on the D15.
I might actually follow you there, but I'm already "over budget" for 2014 after my server re-build project.

The AP-30 fan is really not something you want hanging on any cooler, D14 or D15, unless you plan to control it with a ceiling around 3,000 RPM. But the acoustic-padded duct mod I posted really worked with the fan as case exhaust ported to the cooler.

It is a tantalizing possibility, though. How much air could you pull through a wider -- perhaps taller spin-off of the D14? At what point would enhanced airflow cease to matter? And as I said -- if I could squeeze another 10C improvement out of the D14, what would it be like starting with the few C degrees advantage D15 shows over D14?
 

DrMrLordX

Lifer
Apr 27, 2000
17,247
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I might actually follow you there, but I'm already "over budget" for 2014 after my server re-build project.
Oy, I hear you there.

The AP-30 fan is really not something you want hanging on any cooler, D14 or D15, unless you plan to control it with a ceiling around 3,000 RPM. But the acoustic-padded duct mod I posted really worked with the fan as case exhaust ported to the cooler.
Reports of fan whistle/whine at 4250 rpm aside, 50.5 dBA is probably less noise than my 2-fan combo puts out right now. I forget exactly what they are, but one of them is a Delta, and I think together it's around 55-56 dBA using simple logarithmic addition.

It is a tantalizing possibility, though. How much air could you pull through a wider -- perhaps taller spin-off of the D14? At what point would enhanced airflow cease to matter? And as I said -- if I could squeeze another 10C improvement out of the D14, what would it be like starting with the few C degrees advantage D15 shows over D14?
Oh, goody. Someone asked this question. Time for grossly-oversimplified pseudo-analysis!

There are two ways in which increased airflow improves performance of a heat sink, provided that the heat sink fins are spaced closely enough that additional airflow doesn't pass through the fin stack in a thermally isolated air channel (which can happen in wide fin stacks . . . has to do with the effects of velocity on the thermal boundary layer, blah blah blah). If the air isn't making contact with the fin surface and/or mixing with air that does make contact with the fin surface, then it isn't picking up any heat from the heat sink.

The first (and probably most relevant) way is to examine the total heat capacity of the air passing through the heat sink every second, again making the assumption that all of the air is picking up heat from the fins (we are talking about the D15 which has a really tight fin stack). If we also make the assumption that you're operating in a "best case" scenario in which your CPU/IHS temperature is only rising a few degrees above ambient and that ambient happens to be 27C/300K, we can somewhat-accurately assume that the heat capacity of the air will be around 1006 J/kg * K. Let's say that we want to keep the average fin temperature (again, only marginally relevant due to actual temperature distribution within the fins, but this makes things easier to process) within 1K of ambient.

We have two known quantities: Cp = ~1006 J/kg *K, and delta T = 1. Next we need to know the expected heat flux (in Watts) and the air flow required to maintain the mandated delta T. We can probably calculate the heat flux from tech specs on the processor. For example, if we were cooling an FX 9590 with a TDP of 220W, we could safely assume that it would produce a heat flux of 220W at load.

So (1 / (Cp * delta T)) * heat flux should yield the required mass per second of air flow. In this case, we get ~.219 kg/s. Assuming air density of around 1.1774 kg/cubic meter, we can calculate the cubic meters per second by taking the inverse of the density and multiplying it by the mass flow, giving us a volume flow of ~.186 meters cubed per second, which translates into ~394 cfm.

Of course, some would point out that it's the film temperature that's relevant here, forcing us to use delta T = .5, which would effectively double the required air flow to ~788 cfm.

So, assuming the fin stack can still maintain any kind of temperature differential (1K or higher) over ambient and that that you have no boundary layer separation (which you may) or air flow completely independent of the thermal boundary layer (which you also may), if you want your fin stack to remain within 1K of ambient with a heat flux of 220W, you need around 788 cfm of air flow. Scary. Anything beyond that brings the fin temperatures even closer to ambient at a rate that suffers fairly significant diminishing returns: if we wanted to get the fins within .5K of ambient, it would require around 1576 cfm of airflow, which is so much air that you will probably produce so much extra heat from the fan motors and/or friction between the air and the fin surface that you'd offset the additional benefits of extra coolant flow (assuming we haven't already reached that point @ 788 cfm, which we probably have).

We can also look at the convective heat transfer coefficient, a.k.a. 'h'. In turbulent (or laminar, but our situation is most certainly turbulent) convective heat flow regimes, h tracks upwards as air flow velocity increases. For a situation where you've got heat transfer from a flat plate (which is somewhat approximated by the fins of the D15, but not really . . . ), the average value of h over the plate is ((Pr ^ 1 / 3) * (.036(Re(L) ^ .8) - 836) * k) / L, where:

L = distance from the edge of the fin from its base
Re(L) = (V * L) / v
v = kinematic viscosity
V = Velocity
k = thermal conductivity of the cooling fluid (in this case, air)
Pr = Prandtl number (don't ask)

Without breaking out my ruler and doing some measurements on the D14 in my case (or without doing some research to find the dimensions of the D15), it would be impossible to even approximate the velocity of air flowing through the D14 or D15 @ 394 cfm (or 788 cfm). However, we can see that h tracks upward exponentially with velocity at a rate of V ^ .8 .

The effect that h has on actual heat transfer can be seen either in a simple analysis where you multiply the total fin surface area, A, by your average h value (havg or h(avg)) and the difference between the fin temperature and the film temperature of the air (film temperature = (Tambient + Tfin)/ 2) OR in a more complex analysis where we allow for differences in fin temperature at fin points further and further away from the base, which is messier than I want to get into right now (especially since the fin "base" for the D14 and D15 happens to be six heat pipes, so the fins are more like annular fins than fins extending straight out of a flat base, AND they connect with multiple heat pipes at different points. So messy).

Anyway, in simple analysis, heat flux (I'm just going to call this 'q') = havg * A * (Tfilm - Tfin). So, you can see that there is a linear relationship between h and q: if you double your value of h, you double your value for q. By logical extension, the relationship between q and V (velocity) is also exponential at a rate of V ^ .8.

If you double your velocity, you should see an increase in q of about 140% under ideal conditions where your fins are all of uniform temperature Tfin, which is totally not going to happen, ever. In reality, you'll see less than 140% increase in q.

And, to disambiguate, the value of q I'm specifying here is the expected heat flux that the heat sink can handle given the desired Tfilm and Tfin temperatures.

So, what's the theoretical maximum air flow that could benefit the D15? The answer is "a lot". But really, notable performance increases probably top out at around 300-350 cfm of useful airflow (anything beyond that, and you'll see temp drops of maybe 1K or less). Any airflow that is deflected somehow (ducts prevent this) will obviously be of no use.
 

BonzaiDuck

Lifer
Jun 30, 2004
14,920
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So, what's the theoretical maximum air flow that could benefit the D15? The answer is "a lot". But really, notable performance increases probably top out at around 300-350 cfm of useful airflow (anything beyond that, and you'll see temp drops of maybe 1K or less). Any airflow that is deflected somehow (ducts prevent this) will obviously be of no use.
Thanks for your input on this. My current noise-dampened duct between my AP-30 and the D14 is not the "most optimal," because of the limited space one has for the duct -- with considerations for easier removal while keeping it in a stable and unvarying position.

I may eventually replace the D14 with its successor just out of curiosity. In the meantime, I have enough to do with the target system that it can wait a couple months.

. . . And I'm still amazed at what I was able to do with SPIRE foam-rubber and the art-board . . .
 

DrMrLordX

Lifer
Apr 27, 2000
17,247
6,248
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No problem. It's all very ball-parkish, but I think it provides justification for a). wanting to use ducts and b). wanting to push a ton of air through that thing. Let's face it, some overclocked CPUs out there can produce an insane amount of heat when you take into account the tiny surface area of the die/IHS.

Someday, I may run ducts myself, or do some even crazier things but . . . that can wait for another day. For now, I'll bask in the awe-inspiring glory of the D15 in all its mightyness and suchlike.
 

BonzaiDuck

Lifer
Jun 30, 2004
14,920
1,028
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No problem. It's all very ball-parkish, but I think it provides justification for a). wanting to use ducts and b). wanting to push a ton of air through that thing. Let's face it, some overclocked CPUs out there can produce an insane amount of heat when you take into account the tiny surface area of the die/IHS.

Someday, I may run ducts myself, or do some even crazier things but . . . that can wait for another day. For now, I'll bask in the awe-inspiring glory of the D15 in all its mightyness and suchlike.
Like the time I tried to remove my car's tranny myself for the first time: it took the good part of a day. My functionally illiterate, Thornburg - Virginia, small-time apprenticed car mechanic could do it in less than two hours.

I may have spent four hours on the actual cutting and gluing of the AP-30/D14 duct;several hours thinking about it and a couple hours putting the design on paper with precise measurement for the cutting. Second time around -- with different dimensions . . . given the same basic shape of the cooler and the noise-deadening material around the fan itself separate from the duct -- I may not have to unpower the computer for more than 15 minutes to complete the heatsink swap and duct installation.

Let's suppose, with load voltage drooped to ~1.35 to 1.36 on the SB-K from maximum 1.39V, 75F room ambient, 4.7 Ghz -- I could get it to ~60C average of four-core maximums taken over an hour. How much more electrical noise could you eliminate if water-cooling brought you to 45C?

It really makes one curious. Sooner or later, I'm likely to do it.
 

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