Review of server cooler Noctua NH-D9 DX-3647 4U for Xeon Scalable

Initially, the Intel LGA-3647 platform was created for cloud computing, where a high density of CPU cores in one processor socket is required, but over time, quite good motherboards for workstations on Xeon Scalable appeared, and this year this processor socket looked like A top solution for enthusiasts looking to buy the 28-core Xeon W-3175X and motherboards like the Gigabyte C621 Aorus Xtreme or Asus ROG Dominus. But, of course, solutions from Asus and Gigabyte are rather piece goods for some special cases, and the mass use of Xeon Phi and Xeon Scalable processors is still servers and workstations.

Noctua coolers for LGA3647

Coolers for LGA-3647 are extremely rare on sale, and mainly when assembling a server or a working machine, you will be offered OEM cooling from Dynatron or Supermicro, that is, those solutions where no one thought about the noise level. Noctua has two models for this socket: NH-U14S, NH-U12S and NH-D9 4U with indexes DX-3647. Due to the huge size of the socket, these coolers are not compatible with any other processor sockets, and each of these models is designed for specific needs. For example, NH-U14S with 140mm fan is for desktop workstations where quiet operation is important, NH-U12S is its variation with the new Noctua A12x25PWM fans, and NH-D9 4U is a compact 134mm cooler that will not interfere with neighboring memory modules. , nor PCI Express boards and will not rest on anything.

Noctua cooler NH-D9 U4 D-3647

All three Noctua coolers have two types of mounts: Narrow Type and Square Type, so they are compatible with all motherboards for Socket 3647.

Square ILM vs Narrow ILM

Structurally, the NH-D9 DX-3647 4U is a twin turret for a pair of 92mm fans installed in a push-pull configuration. One fan is installed in the cut of the radiator, between the fins, and the second is outside. Both fans have to be removed during installation, so you can experiment and reinstall them in any other way, since the universal mount allows this.

The NF-A9 HS-PWM fans have PWM speed control and a power splitter is included so you can connect the cooler to one CPU_FAN1 header on the motherboard. However, if your motherboard has OPT_FAN power connectors, on which you can adjust the dependence of the fan speed on the processor temperature, then it is better to connect the cooler to two power sockets in order to maintain the ability to monitor its performance.

Each fan has rubber corners on both sides to reduce vibration and small indentations in the working area of ​​the casing from the side of the blades, designed to reduce parasitic noise. In principle, the minimum speed of each fan is 400 RPM, so even without tweaks in the design, you can achieve silent operation.

SSO2 suspension

The rotor suspension is the most advanced hydrodynamic magnetically centered (SSO2), a reliable frictionless design that ensures complete absence of vibration and, as a result, a MTBF of more than 150,000 hours (17 years). Noctua gives its coolers a 6-year warranty, which is a record in the cooling system market. At a maximum speed of 2500 RPM, the fan has a noise level of 30.6 dB at 56 CFM.

Soldering plates

Radiator Noctua NH-D9 DX-3647 4U has 4 U-shaped heat-conducting tubes with a nickel-plated protective coating. When installing the fins of the radiator, soldering is used, as a result of which the radiator turns out to be eternal, and there is no need to fear the fins peeling from vibration.

Previously, Noctua supplied a syringe with thermal grease in the kit with coolers, but now it saves and applies a layer of thermal interface directly to the cooler base. Of course, processors in servers and workstations are rarely changed by anyone, and such a step will seem logical to someone, but not to us. I believe that the thermal interface should be supplied in a syringe.

The treatment of the base is very interesting: we have here not a mirror polish, but with small notches that you can even feel with your fingernail. In theory, if you have a high flow thermal paste, this treatment increases the thermal contact area with the processor heatspreader. From a practical point of view, it is impossible to measure the difference in temperature between mirror polishing and such honing with improvised means. But here you need to understand that not only marketers, but also real engineers work at the Noctua headquarters, and if you read their interviews, they are very proud when such simple methods manage to reduce the temperature by 0.1-0.2 degrees Celsius. What can I say - romantics!


Due to the fact that the cooler is very compact, it does not overlap the memory slots if it stands sideways to them. But even in this case, the nearest memory module has to be installed at an angle, and if the memory were higher, it would touch the heatsink.


On dual-processor motherboards, two Noctua NH-D9 DX-3647 4U coolers can be installed in a train one after another, getting a cooling system with 4 fans installed in series. Do not be afraid that warm air from the first processor will lead to overheating of the second one: the high air temperature at the inlet is compensated by the higher flow rate in the second cooler, so in practice the temperature will be approximately the same.

As noted by the manufacturer, there are no problems with PCI Express boards, even on EEB motherboards with 7 expansion slots.


  • Processor - Intel Xeon Gold 5120 (14C/28T, 3.2 GHz, TDP 105Wt)
  • Motherboard - ASRock Rack EP2C621D12 WS
  • Memory - 32 Gb DDR4 ECC Reg
  • VMware vSphere ESXi 6.7
  • Windows 10 x64 (6 cores, IOMMU, Hardware Assisted Virtualization, IOMMU)
  • Prime95

CPU core temperature

I had no doubts that Noctua coolers will cope with a 105 W processor. In automatic mode, for the model in question, it makes sense to set the speed control one step lower so that the fans accelerate earlier.

The noise level of 1 cooler Noctua NH-D9 DX-3647 4U at maximum speed is 39.6 dB. When installed in pairs, like on our motherboard, the noise from the four fans rises to 42.3 dB.

Noise diagram

The noise level diagram has a pronounced spike around 280 Hz. The main source of noise is the fan motors, so in most cases when the computer is not running at maximum performance, this noise will not occur. At speeds in the region of 500 RPM, the coolers run quietly, and you can use your computer to edit multimedia content without worrying about blowing your whole brain out with its hum.


Noctua NH-D9 DX-3647 4U is a universal cooler for Xeon Scalable processors, which you can simply keep in stock if you are a collector and periodically order servers on this Intel platform from you. It is equally well suited for rack-mount enclosures and turrets that equip a specialist's workplace. On Xeon Bronze/Xeon Silver series processors, we can say that in a typical mode of operation everything will be very quiet, but under load, the low-frequency rumble will quickly get bored.

As an alternative to liquid cooling, Noctua first of all offers its own quality: solder in the radiator and two fans, which, if desired, can be easily replaced with others. But it should be understood that for older Xeon Scalable processors with a power under 200 W it is better to choose liquid cooling systems.

Mikhail Degtyarev (aka LIKE OFF)

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