Noctua NH-D15S Heatsink Review

Noctua has released its NH-D15S to stand alongside its NH-D15. The NH-D15 is a huge heatsink, a full 15cm wide. The NH-D15S looks like the D15’s twin, also 15cm wide. Where do the two differ? The NH-D15S is moved over to make more room for the first PCIe slot, and it comes with one fan, not two – this keeps the price down. Otherwise they are the same heatsink. Think of the NH-D15S as the high-compatibility version of this heatsink. The single fan configuration gets you a highly capable dual tower cooler with very good RAM and PCIe compatibility. You can add a second fan according to your preference, be it a another NF-A15 if you use standard height RAM or a 120 mm if you need more space. The idea was to give customers more flexibility in configuring the cooler to their needs, be it for maximum compatibility or maximum performance. So let’s look at this heatsink.

Features of the NH-D15S

Noctua provides a list of features on their product page (some descriptive material not reproduced):

High-compatibility version of NH-D15

Excellent RAM compatibility – Thanks to its recessed lower fins, the NH-D15S provides 65 mm clearance for tall memory heatsinks, making it compatible with most high end modules on the market. As the lower fins are recessed on both sides of the heatsink, compatibility is excellent not only on LGA115x and AMD, but also on LGA2011 where there are RAM slots on both sides of the socket.

Asymmetrical layout for better PCIe compatibility

NF-A15 140 mm fan

Dual-fan ready – Using the supplied extra fan clips, the NH-D15S can be upgraded with either a second round-frame 140 mm fan with 120 mm mounting holes (such as the NF-A15) . . . or a common 120 mm fan (such as the NF-F12) for improving performance while maintaining compatibility with RAM modules of up to 45 mm height.

PWM support and Low-Noise Adaptor

Excellent component cooling – Extending below the fin-stacks, the large NF-A15 fan not only contributes to the superb CPU cooling capabilities of the NH-D15S but also provides massive airflow over surrounding motherboard components and heatsinks . . .

SecuFirm2™ mounting system

Compatibility with past and future sockets – Complying with the open SecuFirm™ standard, the NH-D15S can be made compatible with the older LGA1366 and LGA775 sockets using the optional NM-I3 mounting kit, which is provided by Noctua free of charge. If technically possible, Noctua will also provide upgrade kits for future sockets.

NT-H1 thermal compound

6 years warranty – . . . Like all Noctua fans, the supplied NF-A15 features an MTBF rating of more than 150.000 hours and the entire NH-D15S package comes with a full 6 years manufacturer’s warranty.

Specifications of the NH-D15S

Packing the NH-D15S

The NH-D15S comes in standard Noctua boxes with standard marketing on the outside.

Inside, we find squishable foam – my favorite kind. The foam has some give to it and doesn’t break like Styrofoam. The foam surrounds fully recyclable boxes. But you are not going to recycle perfectly good boxes that were custom built for this heatsink and its accessories. The whole thing goes together too nicely. You will keep your box.

When you open the accessories box you find three users manuals – AMD, Intel, and Intel 2011.

Mounting the NH-D15S

Now, let’s pull out this heatsink and take a look. I took this picture upside down, so let’s see the NH-D15S rightside-up. Yup. It is definitely asymmetric.

We will now go through the steps in mounting this heatsink. We will start with the baseplate. The Secufirm2 baseplate is shipped with its own piece of cardboard that fits snugly in the accessories box. Since a little piece of cardboard makes it easy to see what is going on, we will use it to illustrate the mounting process. Note the three holes. They leave room for the three bolt heads you will find on the bottom of Intel sockets. Be sure to mate these holes to make space for those bolt heads. Note also that the four through bolts have been press-fitted to the corners of the baseplate.

Poking through the cardboard from the baseplate are the four through bolts. Put on some spacers and then the brackets on top. The Philips-head thumbscrews tighten down the brackets. You can start them by hand, but you really should tighten them with your screwdriver. Note that the brackets have two threaded shafts. We will get to those. In front of the cardboard is one of the transfer bolts for the LGA 2011 mount.

Those two threaded rods were for the tensioning screws. Noctua provides an L-shaped screwdriver for tightening the tension bolts. However, you would do well to get a 200mm long-shaft #2 Phillips screwdriver. Very helpful for this and for tightening motherboard screw deep in a case.

The second picture shows the NH-D15S with the stock and optional NF-A15 PWM fans. The fan that comes with the heatsink is a 1500 rpm fan. The second fan is a retail model – they run at 1200 rpm. Why would you buy a second fan for this heatsink? If you slow down the stock fan to 1200 rpm with an LNA, you can run this almost silently, and with lots of cooling. But we shall see about that later.

Clips and Clearances

Here is the NH-D15S with two fans installed. Notice how the clips snug up to the finstacks? That’s no optical illusion, as the second picture shows.

The picture on the right shows a standard NH-D15. See how close it stands to the network card in the first slot. In the picture on the right, we can see how the NH-D15S stands a centimeter to the left.

That doesn’t mean the D15 interferes with the first slot. As you can see in the first shot, the finstack clears the first slot by a couple of millimeters. But in a motherboard where the x16 card goes in that first slot (some ATX, most mATX), you would like more clearance. Hence, the D15S in the second shot provides that extra clearance.

Now let us consider RAM clearance. IN the first picture, there is an NF-F12 PWM that provides clearance over a medium-tall RAM heatsink. As you can see, even though you clear the RAM, you also lose more than a centimeter of width on this side. You lose another on the other side. So, although you can fit this heatsink with a 120 mm push fan, you are leaving some cooling power unused if you do it.

The next picture shows you how you can fit a 140 mm fan (an NF-A15 in this case) as a push fan and still not interfere with your RAM – as long as you use low profile RAM.

Finally, if you use no push fan, the finstack will clear even the most ridiculously tall RAM heatsinks, whether they are in front or (as with an LGA 2011) front and back.

Testing Setup

The comparator heatsink was the Noctua NH-D15. Each Heatsink was mounted with a 6 mm blob of NT-H1 TIM. Each time a heatsink was mounted, the TIM was allowed a day to fully spread before the temperature tests were run.

Each test run was 60 minutes in duration. The last 50 minutes of each run was measured, and the temperature logs were analyzed in Open Office spreadsheets. An Intel chip reports its temps in one degree increments, so for best accuracy these reports should be averaged in aggregate. Here the core temps were measured once a second, resulting in 3000-line spreadsheets. The digital thermometer measuring air temp reported its measurements in increments of 0.1 °C. The ambient temperature was measured every five seconds, resulting in 600-line spreadsheets. The mean ambient temp was subtracted from the mean core temps, resulting in a net temp for each run. The net temps were then averaged.

Noctua provided the NH-D15S with its stock 1500 rpm NF-A15 PWM. Noctua also provided a retail 1200 rpm NF-A15 PWM and an NF-F12 PWM. I tested the heatsink with all of these fans.

Since Noctua sent NF-A15 PWM fans for other reviews, I was able to test the NH-D15S with two or three NF-A15 PWM fans. I was also able to test it with two 1500 rpm fans and with two 1200 rpm fans at push and pull with the stock 1500 rpm fan on an NA-RC7 Low Noise Adapter in the middle (in theory, three NF-A15 fans at 1200 rpm). I was able to test the middle fan pulling – both by itself and with a back fan – your normal pull fan. I tested the heatsink with a 1200 rpm A15 in front and the 1500 rpm A125 on the LNA in the middle (in theory, two NF-A15 fans at 1200 rpm).

In essence, I tried to do all the things you might find logical to try. I used two different mounts to compare the cooling. I mounted the NH-D15S a third time with the fans blowing up – I had recently tested the NH-C14S heatsink and found a 5 degree difference in cooling, depending on how I mounted it. So I tried this vertical mount to see if it made a difference in how well the D15S cooled. The results are presented in different charts to keep the different mounts separate.

Finally, I tested this heatsink using OCCT software, running Linpack with no AVX and 1st generation AVX. Since these did not challenge the D15S, I left the results in their spreadsheet.

Results of Testing

NH-D15S vs NH-D15.The first chart below appears to show that the NH-D15S cools 3 °C better than the NH-D15. Relax. What this chart shows is that when you mount heatsinks, your mounts can vary. In fact, you are well-advised to mount and test your cooling, then remount and retest. Stop only when you have arrived at a really good mount.

Within each mount, what this chart does is compare two fans going full blast, one fan going full blast, and two fans running slower than full blast – at about 1200 rpm. With the D15, that means two NF-A15 fans with Low Noise Adapters. With the D15S, that means a retail NF-15 (a fan that runs at 1200 rpm nominal) and the stock 1500 rpm A15 on the LNA. You can compare cooling power and noise in these three fan combinations on each heatsink.

The stock configuration of the D15S is one NF-A15 at 1500 rpm, which is the middle item in the upper group. The NH-D15S cools to 61.5 °C here.

Various fan configurations on the NH-D15S. The next chart shows the second mount of the NH-D15S. The second mount was not as good as that first mount, is it? The stock configuration of one center NF-A15 at 1500 rpm in the second mount cools the NH-D15S to 62.6 °C – 1.1 °C warmer than the first mount. The pair of 1200 rpm A15’s in the second mount cools the heatsink down to 63 °C – 1.7 °C warmer than the first mount. If you were temp-testing your new heatsink, you would remount it and keep remounting it until you were satisfied you had the lowest temp. The NH-D15S was not remounted because the point was to compare various fan combinations to each other. Remounting the fan between tests would ruin those comparisons.

Looking at our results, we see that three fans cool no better than two fans, with substantially more noise. Comparing the pair of 1200 rpm A15’s to a single 1500 rpm A15 shows that the pair of 1200 rpm A15’s cool this heatsink about the same as the single 1500 rpm A15 cools it, but more quietly (Not that the NF-A125 1500 was all that loud).

The 120 mm NF-F12 at 1500 rpm paired with the stock 1500 rpm NF-A15 does OK. But the combination is not as quiet as a pair of NF-A15’s.

The last pair shows one and two fans in pull position. Here we have no push fan in front, but the middle fan is clipped to the front tower while the back fan is clipped to the downstream tower. In this case, a single stock NF-A15 does as well as a stock fan with a retail NF-A15 clipped on in back. After the fact, one wonders if putting the faster fan might have improved the cooling. But that’s for another day.

As usual, slower fans do not cool as well as faster fans, but they work more quietly. But here, running with two NF-A15 fans at 1200 rpm will be very quiet; and if you are willing to remount your heatsink until you get that “golden mount,” you can get very good cooling indeed.

Conclusions

The NH-D15S is at least as good as its predecessor, the NH-D15. It accomplishes Noctua’s main aims of making more room for a 1^st-slot card, bringing down the cost of the cooler, and making this heatsink truly compatible with tall RAM.

Noctua says that three fans are no better than two fans. Testing seems to bear this out. At this point, the sole reason for putting a fan on the back of your heatsink is to engage Bernoulli’s Principle in exhausting your case (this assumes you have removed your rear grill and fan).

Because Noctua provides only a single fan with this heatsink, if you have tall RAM you can use the money you saved and buy a 12cm fan. But really, there is no need for tall RAM in these days of 1.5v and 1.35v memory (even lower with DDR4). Buy low profile or ultra-low profile RAM.

If you want a really quiet heatsink, go with a retail 1200 rpm NF-A15 and put an LNA on your 1500 rpm stock NF-A15. That way your cooling will be just as good, and you’ll never hear the heatsink.

One aspect of Noctua’s heatsinks has not changed: the NH-D15S like the –D15, the –C14S, the -D14 and others, all use the SecuFirm system. If you mount one heatsink, you can swap it for another Noctua heatsink in minutes. They make a reviewer’s job much easier.

NH-D15S Pros

• A premier heatsink, it maximizes air-cooling
• Solid construction
• Easy mounting with Noctua’s SecuFirm system
• Fully compatible with all modern and most legacy CPU sockets
• Quiet, and can be made nearly inaudible
• Compatible with tall RAM, even on two-sided CPU sockets like the LGA 2011
• Comes with clips for another fan
• Comes with Low Noise Adapter
• Fan is PWM
• Noctua will provide hardware for future sockets
• Comes with a generous supply of their really good TIM
• 6 year warranty
• Packing material is fully recyclable
• Comes with explicit documentation
• Full information about the heatsink available online

NH-D15S Con

• Although it is less expensive than water cooling or AIO cooling, high-end air cooling costs.

Availability

The Noctua NH-D15S has an MSRP of $79.90, but availability is early right now, so prices are above list.

Click the stamp for an explanation of what this means.

-Ed Hume (ehume)