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Noctua's DO line of coolers has become a default choice when it comes to quietly cooling AMD Opteron CPUs. Upgrading both compatibility and performance, the new A3 model features Noctua's professional NM-A3 SecuFirm2™ mounting system that not only supports socket G34, C32 and F, but also allows to install the cooler turned by 90°. Thanks to six heatpipes, a performance optimised fin stack and its two premium grade NF-P12 120mm fans, the NH-U12DO A3 cools even the hottest high-end Opteron processors at minimum noise levels. Bundled with Noctua's industrial-grade NT-H1 thermal compound, the NH-U12DO A3 forms a complete premium quality package for quietly cooling AMD workstations and servers.
Details
Performance optimised design

Performance optimised design

The NH-U12DO A3 is based on Noctua's much acclaimed NH-U series which have received more than 300 awards and recommendations from the international press. Six heatpipes, a performance optimised fin stack and an enlarged contact surface suitable for socket G34 allow for further improved performance.
Supports G34, C32 and Socket F

Supports G34, C32 and Socket F

Thanks to the new NM-A3 SecuFirm2™ mounting system that includes brackets with both 3.5" and 4.1" hole spacing, the NH-U12DO A3 supports Socket F as well as the newer G34 and C32 sockets.
Can be turned by 90° for optimal compatibility and positioning

Can be turned by 90° for optimal compatibility and positioning

Noctua's NM-A3 SecuFirm2™ mounting system makes it possible to install the cooler rotated by 90° in order to allow for an optimal positioning of the cooler and to evade compatibility issues on dual socket mainboards.
Drop-in replacement for standard AMD coolers

Drop-in replacement for standard AMD coolers

Screwing directly to the standard AMD backplate, the NM-A3 SecuFirm2™ mounting system makes the new A3 revision a true drop-in replacement. Choose the appropriate mounting brackets, fix the two spring screws and you're done!
2x NF-P12 120mm premium fan

2x NF-P12 120mm premium fan

Featuring advanced aerodynamic optimisations and Noctua's premium-grade SSO-bearing, the award-winning NF-P12 is renowned for its exceptional quietness and long-term stability. The dual fan configuration allows for increased performance and safeguarding against failure.
NH-U12DO A3
Cooler Specification
AMD G34, C32, F (3.5" & 4.1")
Height (without fan)
158 mm
Width (without fan)
126 mm
Depth (without fan)
71 mm
Height (with fan)
158 mm
Width (with fan)
126 mm
Depth (with fan)
95/120* mm
Weight (without fan)
800 g
Weight (with fan/s)
970/1140* g
Material
Copper (base and heat-pipes), aluminium (cooling fins), soldered joints & nickel plating
Fan compatibility
120x120x25mm
Scope of Delivery
  • 2x NF-P12 premium fan
  • Ultra-Low-Noise Adaptor (U.L.N.A.)
  • Low-Noise Adaptor (L.N.A.)
  • NT-H1 high-grade thermal compound
  • SecuFirm2™ Mounting Kits
Warranty
6 Years
FAN Specification
Bearing
Blade Geometry
Rotational Speed (+/- 10%)
1300 RPM
Rotational Speed with L.N.A. (+/- 10%)
1100 RPM
Rotational Speed with U.L.N.A. (+/- 10%)
900 RPM
Acoustical Noise
19,8 dB(A)
Voltage Range
12 V
MTTF
> 150.000 h
NH-U12DO A3

Installation Manual (PDF)

Can the cooler be used in 4U cases?

Common 4U cases usually don’t provide sufficient clearance for tower coolers with 120mm fans and 158mm height. Please thus carefully check whether your case provides sufficient clearance or choose the 9cm variant, which is fully compatible with common 4U cases.

How can I determine if the motherboard’s UEFI BIOS is overclocking my processor by default and deactivate this automatic overclocking?

Most motherboard vendors allow their overclocking-enabled products (e.g. those with Intels X- or Z-series chipsets) to run the processor at increased clock speeds by default, without requiring any user action at all. Since TDP (Thermal Design Power) limits are usually also disabled by default, this leads to the CPU exceeding the rated TDP to a varying degree, depending on the used applications and their workloads. Due to the increased heat output of the CPU, you may see higher CPU temperatures than expected.

In order to find out if your motherboard is overclocking your processor by default, please enter the UEFI BIOS and select the “advanced” or “overclocking” menu. There you should be able to find options such as “MultiCore Enhancement” (options: enabled/disabled), “CPU Ratio Apply Mode” (options: all/per core) or similar. To disable the automatic overclocking, adjust the settings either to “disabled” or “per core” and make sure that the individual multipliers match the original specifications.

In doubt, please contact your motherboard vendor for detailed instructions on how to disable this feature.

My unlocked Intel CPU is running too hot although my heatsink supports the specified TDP, what's the problem?

Intel's unlocked CPUs (K, X and C suffix) can dissipate more heat than indicated by the TDP specification if
  1. the TDP limits are extended or disabled in the motherboards' BIOS.
  2. the motherboard applies automatic overclocking by default, e.g. by raising the supply voltage of the CPU and using higher Turbo-Mode multipliers.
  3. some software creates untypical loads, e.g. Prime95 with AVX2 support and a) and/or b) apply.

This can lead to temperature issues, especially when using smaller coolers or compact cases.

The actual power draw of the processor can be monitored with software provided by the motherboard vendor or with 3rd party tools like HWInfo or HWMonitor.

If you encounter temperature issues (>90°C) and notice a higher than specified power draw, please ensure that no automatic overclocking is applied and limit the TDP to the specified value by choosing appropriate BIOS settings.

For Kaby Lake CPUs, it may also help to lower the CPU clock speed for applications that heavily use the AVX instruction set, which can lead to higher loads and power draw. This option is usually referred to as “AVX offset” and makes it possible to lower the multiplier specifically for AVX based applications without reducing performance when using other instruction sets. Depending on the quality of the CPU and the programs being used, a reduction of 2-3 steps usually gives very good results.

Please contact your motherboard vendor for details if you have trouble finding the appropriate settings in the BIOS.

All our TDP recommendations are based on thorough testing with the default values specified by Intel using popular applications such as Asus Realbench and prime95. Please note, however, that prime95 creates a particularly high load that goes beyond typical application scenarios and this leads to elevated temperatures. We thus recommend using other programs such as Realbench for checking the stability and temperatures of the CPU in realistic scenarios.

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