Individual Component Testing
1) MasterLiquid Pro 140 Pump
Cooler Master does not recommend slowing the pump down, as with any other CLC selling company in general. There are some good reasons for this- pump lifetime is tested at full speed only, and some pumps do not like any sort of pump control- especially voltage control. Secondly, CLC pumps aren’t the strongest performers to begin with so you really need everything it can throw out which happens to be at full speed. However, there are some occasions where pump control is handy. If an air bubble is stuck on the pump, slowing it down and increasing the speed again can help re-locate it elsewhere where the pump will not sound harsh. Given this is a review sample, I went ahead and tested out PWM control on the pump to give you an idea. Well, there is no PWM control here. Despite the pump cable having a 4-pin connector the pump itself is not a PWM device. It, however, does respond to voltage control and so I used an Aquacomputer Aquaero 6 XT for both voltage provision and RPM readout:
Before you start questioning those numbers, let me point out that the pump does not actually run at ~9500 RPM at 12 V. That would be extremely loud for a pump like this. The pump used here does not have a 1:1 RPM readout, and Cooler Master told me the actual pump speed is the readout divided by 3. So the actual max pump speed here is 3175 RPM. Keep this in mind, as the graph below will have the actual pump speed instead as a function of voltage provided and power %. Also here is the pump noise measured inside an anechoic chamber of size 5′ x 8′ with ambient noise level ~19 dBA and a sound probe held 6″ away to measure the sound volume in dBA accordingly.
As we saw before, this pump maxed out at 3175 RPM at 12 V and went all the way down to 1460 RPM at 4 V before shutting down. It restarted at 4.4 V for those who care, but note that the pumps is fairly quiet at all times. This is important in determining if it is worth setting up a pump on voltage control or not- especially if the manufacturer does not recommend it.
To provide some context, here is the pump on a couple of new single 120 mm AIOs from Corsair and Silverstone:
Note that all three pumps have different designs, different max speeds and potentially different P-Q numbers as well resulting in different flow rates in a common loop if that was ever a thing. Given how these CLCs are all not meant to be expanded, the only useful metric here is pump noise and the Cooler Master pump is ever so slightly less audible.
2) Masterfan Pro 140 Air Pressure fans
Testing was done with the fans mounted one at a time on the MasterLiquid Pro 140 radiator, with the fan controlled using an Aquacomputer Aquaero 6 XT in PWM mode. The controller also enabled RPM readout. This was done to chart RPM vs PWM in the 3 modes available on the fan. After this, both fans were installed in push-pull with the provided rubber gaskets and linear airflow was measured using an Extech 45158 Thermo-Anemometer 6″ away from the fans such that it measured the airflow in feet per minute through the radiator. Fan noise was measured in the same anechoic chamber of size 5′ x 8′ with ambient noise level ~19 dBA and a sound probe held 6″ away to measure the sound volume in dBA accordingly with the pump not powered on so the fans were the only source of noise.
S (Silent) mode is rated for 650 to 1550 RPM and these fans went from an average of 1562 RPM at 100% PWM to 597 RPM at 25% PWM. Q (Quiet) mode is rated for 650 to 2200 RPM and these fans went from an average of 2179 RPM at 100% to 631 RPM at 25%. P (Performance mode is rated for 650 to 2800 RPM and these fans went from an average of 2822 RPM at 100% to 655 RPM at 25% PWM. All 3 modes were well within the error margin I allow, and in some cases even over-delivered which is nice to see. This is especially impressive considering these recordings were with the fan up against airflow restriction too. That being said, keep in mind that this is all of 1 fan in the test pool. Also, surprisingly, the fans switched off below 25% PWM in each mode rather than continuing to remain at the same fan speed all the way down to > 0 %. Knowing that the largest operating speed range was in P mode, I measured noise and airflow through radiator for it accordingly.
A couple of things to note here. The fans at their lowest speed are collectively about the same as the pump at its highest level (without any air bubbles stuck, anyway) so yet again it really is not worth having any voltage control on the pump here and it’s best to leave it at full speed during regular operation. Secondly, this is another extremely loud cooler! I honestly can’t imagine running this with both fans at full speed if I have this installed in a case a few feet away. For some context, here are some single 120 mm CLCs with their stock fans in push-pull:
They are all loud! But note that the airflow numbers are much higher here on the MasterLiquid Pro 140. One factor is of course the use of 140 mm fans on a 140 mm radiator vs 120 mm fans on 120 mm radiators, and another is the fin geometry and density here. The radiator on the CM MasterLiquid Pro 140 has small, square fins at 19 FPI which does have less airflow restriction compared to serpentine fins at 22-23 FPI, all other things being equal. The only other change is the increase in number of coolant tubes here but the fin geometry overcomes that. Overall, it is promising of better low fan speed performance compared to other CLCs which is a very important thing considering noise levels. So let’s get right to it and test thermal performance on the next page.