Cooling Efficiency

We are going to start with a not quite common diagram. It shows the results obtained with Thermalright AXP-140 with a 140-mm Scythe Kaze Maru fan working at different speeds and with different CPU clock frequency and Vcore settings. The idea behind this test is fairly simple: at first we determined the maximum CPU frequency at the lowest fan rotation speed of 535RPM. Then we increased the fan rotation speed two steps up, by about 300-400RPM each, without overclocking the CPU any further. Then we once again found the maximum CPU frequency for each next fan rotation speed, and so on and so forth. The results were summed up in the following diagram:

As we see, even in the quiet mode at 535RPM fan rotation speed, Thermalright AXP-140 can cope just fine with a CPU overclocked to 3620MHz at 1.45V Vcore running heavy-duty Linpack test. It is a very good result, because the load created by Linpack is sort of unique, the noise from the cooler is minimal and besides, HTPC systems will never work in conditions like that. This allows us to conclude that Thermalright AXP-140 working in quiet fan mode will do perfectly fine with any existing processors.

If you value noiseless systems then you would be really interested in the results obtained at 840RPM and 1180RPM. In the first case, our quad-core processor overclocked to 3825MHz at 1.55V Vcore, which is only 25MHz short of the maximum this CPU can do in Linpack. Further tests with Thermalright AXP-140 didn’t generate any new results, although we could lower the CPU temperature by 4°C and 1°C at 1500RPM and 1860RPM respectively. So, we can state that the new Thermalright AXP-140 cooler becomes more efficient as the rotation speed of the 140-mm fan increases from 840 to 1500RPM. Speeding up the fan further doesn’t really justify the significantly increasing noise.

The next diagram will compare the cooling efficiency of our today’s hero against Thermalright Si-128 SE:

As we remember, Si-128 SE has been so far the best “top” cooler (i.e. a cooler with the airflow directed to the top of the mainboard). Now we can pronounce Thermalright AXP-140 our new leader in this category. It managed to win 2-3°C from the former champion under maximum workload. Yes, the 140-mm fan does play an important role here. When we replaced it with a 120-mm one, the temperature increased by the same 2-3°C. However, a 140-mm fan installed onto a SI-128 SE doesn’t do any additional good (the results are even 1°C worse than with a Magma fan, because Scythe Kaze Maru has a larger rotor and less focused airflow).

But this is also not all yet. In conclusion I would like to offer you the results of maximum CPU overclocking and its thermal readings with each of the today’s testing participants at the maximum fan rotation speeds:

Both highly-efficient cooling solutions ensured CPU stability at 3825MHz and 1.55V Vcore. However, Thermalright AXP-140 turned out 6°C more efficient in this mode than its counterpart. And although the noise level is 1.1dBA/1m not in its favor, we are still truly impressed.