Page 2 - Physical Look - Hardware; Installation
It is clear that when Cooler Master called their MasterAir MA624 "Stealth", they were referring to its all-black exterior. This makes the whole package look sleek and blend into practically any system build, unless you are going for a full white look. Rather than exposing the top of the two towers of fins, Cooler Master has slapped a large metal shield with a brushed finish on top. While I appreciate this large plate for some other reasons we will explore during the installation, I also wish Cooler Master could have kept their branding a bit stealthier than the large Cooler Master logo pasted in the middle. Rather, they could have accomplished this by using their outline logo or a matte black logo. Even so, I think this is a pretty attractive CPU heatsink. Aesthetics may not necessarily matter too much when it comes to cooling, but I still appreciate it. The entire unit is made up of a mixture of copper, aluminum on the heatsink fins, and some nickel plating to boot.
On the other hand, I am not sure if many people would describe the size of the whole MA624 as stealthy, especially with its massive footprint. Similar to larger heatsinks like the Noctua NH-D15S chromax.black, the Cooler Master MasterAir MA624 Stealth features a larger dual-tower style cooler. The fins are not exactly visible from this vantage point, but there is a slight indentation towards the middle of the heatsink. Otherwise, the fins are pretty flat. There are a total of 43 fins on each tower, but some of the fins closer to the base have been cut away to provide greater compatibility for taller memory modules. The spacing between each fin is approximately 2.0mm, although there was some variance in spacing between some fins. From my calculation, the total surface area of the cooling fins combined is approximately 1.05 square meters, which is slightly smaller but comparable to the aforementioned NH-D15S chromax.black. At a total mass of 1.09kg with a single fan installed, this is a pretty hefty cooler. For some reference, the Noctua NH-D15S chromax.black weighs in approximately 1.15kg with its single stock fan attached.
The single fan mounted on the Cooler Master MasterAir MA624 Stealth is mounted in between the two heatsink fin towers with plastic clips. Unfortunately, this middle fan is a bit tricky to remove because you must take off the large shield at the top, which does not seem quite easy. However, the fan does not protrude out from any side further than the heatsink, so you probably will not need to move this fan. From this angle, you can also see a large metal rod going down each side of the heatsink towards the base. This is like an extended screw that sits on the top of the heatsink so that users do not need to actually remove any fans or such when installing the MasterAir MA624 Stealth.
Taking a step back, the Cooler Master MasterAir MA624 Stealth dimensions are pretty big, but this is not too surprising for a cooler with a 140mm fan attached. It measures 160 mm in height, 153 mm in width, and 145 mm in depth. With a second fan installed, the depth increases by an additional 25 mm. At this 160 mm height, this is definitely a taller heatsink and you may run into troubles depending on the enclosure you have. The MasterAir MA624 is symmetrical and slightly overhangs into the memory area even without the fan installed. However, due to the cutout of the fins near the bottom, users should be able to install memory modules up to 70mm in height, which should accommodate most RAM sticks. If you install the second fan on the intake side, you will be limited further, depending on the size of the fan you install.
From the base where the metal makes contact with the processor, six continuous U-shaped heatpipes lead away from the CPU contact, splitting into two fin stacks. This effectively makes twelve heatpipes in total. The heatpipes are supposed to efficiently lead the heat away from its source due to the low heat of vaporization, or phase change energy, of alcohol. The heatpipes are aligned in manner to spread out the heat in the dual array of radiating fins. The 1.05 square meters of surface area, combined with an assortment of SickleFlow fans, should be able to deliver very good heat dissipation performance, but we will see if this statement is true on the next page.
As for the fans in question, we have an assortment of Cooler Master SickleFlow fans. Cooler Master has included three fans with every MasterAir MA624 Stealth for various configurations. From the picture, you can see we have three fans included with two being the larger 140mm size and the last one being 120mm. Both of these fans use rifle bearings internally. The two 140mm fans have a rotational speed range of 650 to 1400 RPM, maximum airflow rating of 67 CFM, and maximum static pressure of 2.25 mmH2O. The 120mm fan operates within a range of 650 to 1800 RPM, maximum airflow rating of 62 CFM, and maximum static pressure of 2.5mmH2O. While traditional rifle bearings do not necessarily boast the longest life, these ones offer up to 150,000 hours. These fans are attached to two plastic brackets, which screw into the fan and attach to either side of the MA624 Stealth. When it comes to the active components of this cooler, I do appreciate the inclusion of this smaller fan as it means users can install it at the intake side if you need more clearance near the memory modules. However, I would have liked to see the use of wire brackets instead of plastic ones for more flexible placement and so less work is needed when swapping out for the smaller fan. Alternatively, it would have been nice to see one more set of brackets so users could install all three fans too.
The photo above shows a shot of the bottom of the Cooler Master MasterAir MA624 Stealth CPU heatsink and the configuration of the heatpipes more clearly in relation to the base leading into the fin array. You can see the base is very flat, which means practically the entire base should rest evenly on top of the processor. A quick inspection also reveals there are no abnormalities here, although on closer inspection, you can see the finish here with a radiating circular mark to flatten the surface. As well, you can tell they have used the stealthy black finish everywhere except for the base, which is expected. This heatsink is composed of copper, nickel, and aluminum. The base and heatpipes are built using copper for best heat transfer ability with a thermal conductivity of 401 W/mK. The heatsink fins utilize aluminum as it is a bit lighter in comparison to copper. This compromise allows the MasterAir MA624 to reduce its weight and thus reducing the stress on the motherboard. Aluminum has a thermal conductivity of 237 W/mK, which is not as optimal for heat transfer, but the trade-off is understandable.
Visually speaking, the Cooler Master MasterAir MA624 Stealth conceals the copper color with a nickel-plated cover. The electroplating of the base with nickel on top of copper has a thermal conductivity of only 90.9 W/mK. While nickel has a lower thermal conductivity than copper, the electroplated layer is very thin and should not directly affect performance to a significant degree. Instead, this is done this way to keep the base from corrosion. Nickel and nickel-base alloys generally have desirable properties that can withstand corrosive environments and high temperatures, which are especially beneficial for a heat dissipation device. The reason why nickel has such a property is because of nickel's ductility and toughness all the way up to the melting point of 1455c, measured at non-standard pressure. Nickel's face-centered cube crystal structure is virtually unaltered all the way up to that temperature. Nickel, like titanium, is highly resistant to corrosion so corroded material will not build up on the surface in the long run. As a result, the Cooler Master MasterAir MA624 Stealth will be less prone to losing its cooling performance over time as juxtaposed to a corroded copper surface.
Additionally, all the joints are cleanly soldered at the base while the heatpipes are soldered to the fins. Pressed fins are typical for most heatsinks, but this can lead to degradation over time as contact between metals decreases due to thermal expansion and contraption. Cooler Master also highlights this should reduce any sort of air gap between the pipes and the fins. Overall, the Cooler Master MasterAir MA624 Stealth appears to be built very solidly, though some of the fins are slightly bent closer to one another. It is nothing out of the ordinary and these uneven gaps can be bent back to their correct position. Reliability should also be excellent but Cooler Master offers a five-year warranty should anything go wrong.
The installation of the Cooler Master MasterAir MA624 Stealth is one of the easier heatsinks to install despite its large size. Even so, I will walk you through my process and why it was made so easy. Starting at the back of the board, we have a plastic backplate to be used with either Intel or AMD motherboards. Users can install the necessary parts into this backplate and secure the mounting standoffs with plastic caps. If you are using an Intel motherboard, be sure to flip this backplate over before installing it into place.
On the other side, users can attach four screws and mount two mounting bars. This process may look very similar to Noctua's SecuFirm2 system, which is a good thing considering how easy it is to install Noctua coolers. These bars are screwed down with some thumbscrews and then users can place the Cooler Master MasterAir MA624 Stealth on top. As we have already seen, the installation screws on the heatsink are located at the top, so users do not need to use the L-shaped screwdriver provided. Before doing so, be sure to place a bit of thermal paste between the processor and the heatsink. Next, place the MasterAir MA624 Stealth on top and screw it in, alternating sides to apply even pressure to both sides of the mounting hardware. I do appreciate how easy access the mounting parts are, especially since it means I do not need to remove any fans to get the whole heatsink mounted. With just the single fan installed, nothing interfered with my RAM, even as it does slightly hang over the slots. If you add a second fan attached the front side, this may affect clearance further, especially with the larger 140mm fan here. Even so, I am happy with this whole installation process, which was a painless process.
1. Introduction, Packaging, Specifications
2. Physical Look - Hardware; Installation
3. Test Results