Axagon CLR-M2XL: Only one SSD cooler can be the best

The Axagon CLR-M2XL cooler in detail

The designers have really gone all out with the CLR-M2XL cooler. Some of the details are really surprising for an SSD cooler, but you can see a clear intention – to squeeze the most out of the available material. Finding a more powerful model than the CLR-M2XL in the current offer among passive SSD coolers will be very difficult, with a better price/performance ratio probably impossible. Despite the superior cooling performance, Axagon held back on pricing.

The Axagon CLR-M2XL cooler in detail

The contents of the package consist of the cooler itself, a backplate, thermal pads and screws. We will break all these things down one by one.

The heatsink is made of aluminum and Axagon used quite a lot of it. However, it is not the heaviest SSD cooler we have tested in our time. Some heatsinks that come with motherboards have a higher weight than the 74 gram CLR-M2XL. With none of them, however, has the manufacturer broken down the surface area as significantly as is the case with this Axagon heatsink, which has the largest “shell” area by a long shot. This is achieved by a combination of long and short fins. In both cases, these are directed longitudinally.

The short fins increase the radiating area on the outside of the outermost fins. However, the long fins in between are the key. The base is quite thick, and at 8 mm in height, it makes up as much as the overall height of other SSD coolers. This does give it the advantage of greater absorption capacity, although it should be noted here that it is an aluminium monolith. This means that the conduction of heat from the SSD to the fins of the heatsink is a little slower than it would be if copper or even better, if a heatipe was used. However, such designs would be considerably more expensive and in the case of the CLR-M2XL cooler, the emphasis was again on the best possible price/performance ratio, as is Axagon’s habit with its products.

Considering the determined production costs, it is not possible to make a significantly more efficient design out of aluminium alone. That is, if the best possible compatibility with the surrounding components is to be maintained as far as possible. The only limitation here is basically the height. It is as much as 32 mm, so you can’t install the cooler in a slot above which the body of a PCI Express expansion card (typically graphics card) extends. However, the CLR-M2XL does not significantly exceed smaller coolers in width (22 mm) and neither does it exceed them in length (75 mm).

Only 80 mm M.2 SSDs are supported, which is perhaps a bit of a shame from the perspective of users needing better cooling on 110 mm models, but here Axagon was faced with the choice of either one (80 mm SSD) or the other (110 mm SSD) and opted for the former. At length, the heatsink cannot extend beyond the SSD as it would either encroach into the space above the contacts (SSD) or above the cutout in the PCB to screw to the spacer post. Therefore, support for smaller SSDs (60 mm and shorter) is also eliminated.

Up to three types of thermal pads come with the cooler, and here it’s not about having some duplicates (to spare), as is the case with the CLR-M2Lx coolers. The thinnest pad, which is white on one side and red on the other, is the thermally conductive interface between the chips (the white, smoother side is put on those) and the heatsink. And then there are two thicker, blue pads, one of which is wider. A close look also reveals that it’s cut into 12 × 12 mm squares across its width. These are for SSDs that have a larger height difference between the controller and the memory chips. On such, using only a thin, white-and-red pad would not ensure optimal contact with the heatsink. A third pad (the second blue, narrower one) is installed between the back of the SSD and the backplate.

The backplate is screwed to the heatsink at three points on each side. Two mounting holes are in the front, two in the back and the third pair is in the middle. To what extent this solution improves the downforce (with the backplate, which thanks to the U profile won’t bend easily) is difficult to note, but this central reinforcement certainly doesn’t do any harm.

The mounting holes on the backplate are oval to allow installation on thicker SSDs (with chips on both sides) and thinner SSDs (with chips on only one side). To achieve a stable position, the screws need to be tightened properly, but naturally in moderation, so as not to shear the thread, you screw into the “soft” aluminum.

One more note on the backplate: note the pinholes on the surface of the entire shell. These increase the overall surface area of the shell, which you don’t really see with other SSD coolers. Partly because when cooling such low power draw as SSDs have, such a technical improvement doesn’t show up too much (specially, on the backplate, which is like a secondary element in terms of heat dissipation from the SSD), but it’s a very nice detail from Axagon. It oozes a kind of “enthusiasm” and interest to do something extra, beyond the grey average.

To conclude the introduction of the CLR-M2XL, once again a warning that this cooler is really tall and you have to install it in a slot (M.2) that has nothing overlapping on the top. In mini PCs, the side panel of the case must also be sufficiently spaced apart.


The tests take place in a wind tunnel that replaces a standard computer case. Four Noctua NF-S12A PWM@550 rpm fans are used for system cooling in a balanced ratio of two intake to two exhaust fans. The intake air temperature is strictly controlled and is kept within a narrow range of 21–21.3 °C for maximum accuracy.

In line with findings from measurements of the impact of different positions on cooling efficiency, we test separate SSD coolers in the first slot, above the graphics card. From board tests we naturally have a lot of results of coolers (referred to as cooler 1 and cooler 2) from other positions as well, but there it is due to their fixed position.

For testing, we use the Samsung 980 Pro SSD (1TB). The load is run for 10 minutes (which is enough time in the wind tunnel for temperatures to stabilize) in CrystalDiskMark – sequential read and write cycles. The achieved power draw then is about 8 W, which is the upper limit of what M.2 SSDs achieve and shouldn’t change even models with PCIe 5.0 interface support.

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Comments (2) Add comment

    1. This heatsink is designed for a disk used as a buffer. But good point. I have disks cooled by massive 3 cm heatsinks (more massive than the reviewed) and their idle temperature is definitely not below 30°. But I also have low airflow in the case.

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