Conclusion
The original fans are quite slow, so it was especially fascinating to watch how the heatsink behaved with settings that are not intended for it – with a proper airflow through the ribs. Not only with both fans, but also with just one. Some results really surprised us. And the temperatures in the passive mode are very interesting too, one of the reasons why Ninja coolers have such a good reputation.
Bonus tests of coolers are a regular extension of standard reviews. In addition to cooling efficiency around the socket, they include testing and comparison of heatsinks using the same fans, as well as fully passive operation without any active cooling. And also other various tests that might be interesting for a particular cooler.
How we were testing
During the tests, we also measured CPU MOSFETs heating at 33 and 39 dBA. We put the sensor right into the heatsink. These tests always begin with the same starting temperature (35 °C). Although Gigabyte is known for an excellent cooling of its power supply and manages to maintain very attractive temperatures, it is still easy to determine which of the coolers more or less keeps doing a good job cooling the critical components.
The fans were aligned in such a way that they do not exceed over the top rib because it would be pointless there. It is more important to swirl the air in the lower parts. This was still measured with the default fans.
In the next phase of the tests, the original fans were replaced by the reference fans to create the performance comparison of the heatsinks with the same fans. These results might come in handy when you want to replace the default fans. Usually because they are too fast or too slow (and inefficient), or they produce disturbing sounds, or for whatever reason based on personal preferences.
Optimal candidates for such tests are the “industrial” Noctua NF-F12 iPPC fans. Thanks to their wide range, we could test with a very high flow and at a very low noise level. We increased the flow of the system fans (4× 1200 rpm) only in 24 V mode (2000 rpm without any problems). For a better comparison, we also included the tests with standard 4× 550 rpm. After reducing the voltage to 15 V, the fans were relatively quiet (1290 rpm) and at 9 volts they were running at 765 rpm only, which could be especially challenging for large two-tower heatsinks and larger liquid coolers. We replaced the reference fans with the number corresponding to the original set. Usually one or two. For a better orientation, it is marked in the charts (1/2 ×).
Finally, the coolers competed with each other without a fan. The processor we used was Core i7-5930K (TDP 140 W) with Vcore 0.9 V, which had 25 W lower power consumption than with default settings. These tests took longer than those before, 900 seconds. Most coolers cannot handle this. After 95 ºC, tests were interrupted and considered unsuccessful. Therefore, temperatures in idle are also interesting. We used traditional configuration of system cooling and airflow.
The original fans are quite slow, so it was especially fascinating to watch how the heatsink behaved with settings that are not intended for it – with a proper airflow through the ribs. Not only with both fans, but also with just one. Some results really surprised us. And the temperatures in the passive mode are very interesting too, one of the reasons why Ninja coolers have such a good reputation.
Cooling the MOSFET-s
| Cooler | Cooler | Speed and voltage of the fan | |||
| Cooler | Cooler | 39 dBA | 31 dBA | 33 dBA | 31 dBA |
| Arctic Freezer 33 | Arctic Freezer 33 | 1× 1148 rpm | 8.8 V | 1× 848 rpm | 6.23 V |
| SilentiumPC Fera 3 v2 | SilentiumPC Fera 3 v2 | 1× 1393 rpm | 9.4 V | 1× 971 rpm | 6.59 V |
| Noctua NH-D15 | 2× 1073 rpm | 8.1 V | 2× 700 rpm | 5.87 V | |
| Reeven Okeanos | 2× (1044 + ? rpm) | 7.77 V | 2× (800 + ? rpm) | 7.58 V | |
| Scythe Fuma rev. B | 2× 923 rpm | 7.19 V | 2× 821 rpm | 6.37 V | |
| Scythe Ninja 5 | – | – | 2× 692 ot./min | 8.45 V |
The original fans are quite slow, so it was especially fascinating to watch how the heatsink behaved with settings that are not intended for it – with a proper airflow through the ribs. Not only with both fans, but also with just one. Some results really surprised us. And the temperatures in the passive mode are very interesting too, one of the reasons why Ninja coolers have such a good reputation.
With the same fans
The original fans are quite slow, so it was especially fascinating to watch how the heatsink behaved with settings that are not intended for it – with a proper airflow through the ribs. Not only with both fans, but also with just one. Some results really surprised us. And the temperatures in the passive mode are very interesting too, one of the reasons why Ninja coolers have such a good reputation.
Passive mode
Prints after the disassembly
The original fans are quite slow, so it was especially fascinating to watch how the heatsink behaved with settings that are not intended for it – with a proper airflow through the ribs. Not only with both fans, but also with just one. Some results really surprised us. And the temperatures in the passive mode are very interesting too, one of the reasons why Ninja coolers have such a good reputation.
Conclusion
Let’s go chapter after chapter. Traditional bonus tests include monitoring of VRM heatsink temperatures. This was the only bonus test when the stock fans were still installed. Ninja’s heatsink puts both fans further away from the power supply circuit than other coolers do, and the overhang of the rotors over the ribs is less significant. It is therefore quite obvious that the fans have lesser impact on the cooling of power supply circuit. However, we’re not trying to say that Ninja 5 is insufficient in any way, the results in this discipline are just negligibly worse than those of other tested coolers.
With a very strong system airflow, the fifth Ninja is falling behind NH-D15 only by 3 °C, which is a great result for Scythe since their cooler is noticeably cheaper. After reducing the system airflow (the speed of CPU fans was still 2000 rpm), the difference deepened a bit and this unique heatsink started to behave strangely. In this single mode, the cooler was more efficient with one fan only. The second fan pulls a lot of air in a linear direction (we’re still talking about high RPM), which seems to be not working well with the design that benefits from air dispersion. If you want to get the maximum performance out of this cooler, you simply need to use a strong system airflow, although such noisy settings may not be attractive for everyone.
Medium speed of the reference NF-F12 iPPC fans worked out better for Ninja (it could almost keep up with NH-D15), and low RPM would be the best choice. But we need to mention that Noctua cooler comes with two bigger fans that really fit its heatsink and thus make it more efficient, and the same can be said about Ninja 5 (Scythe fans have more blades with smaller area and larger angle). The results confirmed the fact that Scythe worked hard on optimization of their fans. Look at the temperatures with stock models at max. RPM (72.3 °C) and with 2× NF-F12@15 V at max. RPM (72.5 °C). It’s basically the same value + original Ninja fans running at maximum speed are 6 dBA less noisy.
Removing one fan ruins the cooling performance only at very low noise levels, but we still don’t recommend doing it. If you want to have a quiet rig and are planning to buy the cooler with intention of using the second fan for your system cooling, you should reconsider it. Ninja 5 is optimized for two fans with low RPM. Results in the passive mode are also convenient, but Ninja 4 could handle it definitely better thanks to narrower gaps between the ribs.
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