DeepCool Assassin IV review

Jun 01, 2023

Only a few years ago, be quiet! and Noctua were largely recommended for top-class air coolers. For a few years now, DeepCool has also been mentioned more and more often in this context. With the Assassin III, for example, they have brought a massive 140 mm cooler onto the market that plays in the top class in terms of performance. Then in 2022, the new AK series hit the market with the DeepCool AK620 as the top model – with a clean look, low volume and performance that again just scraped the level of the Assassin III. But the development does not stand still and DeepCool continues to develop its coolers at an almost confusing pace, so that now the successor of the Assassin III appears with the Assassin IV. And that in a completely fresh and even cleaner design. What this new high-performance cooler has to offer, we now see in the DeepCool Assassin IV test!

The packaging design is similar to other recent DeepCool coolers. A brown cardboard box is partially covered by a white cover with the product imprint. Thus, DeepCool stands out from the previous playful design and goes the serious way. The white cover has to be peeled off to the side to open the box. Inside, you first see black foam and a brown cardboard box. This brown box contains the necessary accessories. If you remove the upper layer of the black foam, you look directly at the top of the very square cooler. On the other side, you will find the foam counterpart. This way, the cooler is securely wrapped and even more violent blows should not cause any damage during transport.

The accessories are in the small included cardboard box. A screwdriver, thermal paste and a cleaning kit, mounting materials, instructions and a frame for mounting an additional fan can be found in here. A set of case fan screws is also included for this. However, these do not have a Phillips head, but a small hexagon. The screwdriver in the scope has accordingly on one side a cross-slot for regular mounting and the hexagon for the case fan screws.

The design of the DeepCool Assassin IV completely stands out from the crowd. Where the DeepCool AK620 already had a fairly clean, square look, the Assassin IV steps it up even more than a notch here.

So it’s no surprise that it even picked up design awards. The look of this giant (and this is the DeepCool Assassin IV!) is continuous, high quality, and there is no fan at all on the front from the factory. Instead, you have a clear view of the DeepCool signature square pattern of fins. Still, the cooler has two fans. A 140mm fan sits below the grille area and a reversed fan sits in the back, so you won’t see any ridges of the fan frame in its pull configuration.

The build quality of the DeepCool Assassin IV is shown to be very high in testing. The top grille that covers the 140mm fan is held very securely by magnets. The weight is high, which provides some mass for heat dissipation. The frame around the blades also looks high-quality and is made of a pleasantly textured plastic.

Mounting the DeepCool Assassin IV goes quite well by the hand. For Intel, a sturdy backplate is included and for AMD, the existing backplate is used. The test system uses an AMD Ryzen 9 5950X, ergo AM4. Here, the backplate is secured with a couple of thumbscrews – onto these come the brackets, which are secured with thumbsnuts. Now it’s the turn of the DeepCool Assassin IV heatsink. First, the magnetic protective grille on the top has to be removed to access the 140 mm fan. This is pulled out upwards to get to the mounting mechanism with the screwdriver. Now the thermal paste is applied to the processor and the protective foil is removed from the contact surface of the heat sink. The visible fan should point towards the back of the case to ensure a constant air flow.

Next, tighten the DeepCool Assassin IV to the sturdy brackets. Once you’ve reached the stop, all that’s left to do is slide the fan back in. When doing this, you have to make sure that you thread the cable of the fan back in sensibly. Finally, you only have to click the magnetic grille back on. The installation is thus very reminiscent of Noctua coolers. That means it’s really easy and fits securely in the end.

With the heatsink in place, the Giant sits on the motherboard. By the way: the rear fan can be pulled out backwards together with the mounting part and placed higher up to be pressed tight again. This is especially relevant if you have a larger platform with quad-channel RAM, where you have RAM sticks both in front and behind the socket. This way you avoid the rear fan colliding with the rear RAM sticks.

With the appropriate mounting frame, it is possible to mount a third fan. Thus, the fan is attached to this frame with case fan screws and then the frame is put on the cooler from the front. The problem in this case is the case fan screws with the hex head. When mounting an additional DeepCool FK120 (€ 13.99 *), two of the screws were reasonably easy to screw in, one was difficult to get into position, and on the last one it completely broke the head of what seemed to be a fairly soft screw. In the end I removed the supplied screws and used regular screws with Phillips heads, which then worked without a problem.

Once the frame with the additional fan is attached, you can adjust its height to avoid conflicts with the RAM. This is especially relevant if you are not using a 120mm fan, but a 140mm round frame fan with the hole spacing of a 120mm fan, which is common on 140mm coolers. The hole for the air passage in the frame is also designed for such fans. A 120 mm fan, like this DeepCool FK120, looks a bit out of place anyway.

In the DeepCool Assassin IV test, I compare in particular with the already repeatedly mentioned AK620, which is one of the strongest air coolers that have been available so far. In addition, it is also a good bit cheaper than the Assassin IV.

The thermal paste included with the Assassin IV is used for both coolers. I also use the Performance mode – this lets the fans of the DeepCool Assassin IV get a bit louder than the Silent mode, but gives all the performance the cooler has to offer.

The test is performed on an AMD Ryzen 9 5950X, which draws over 150W with an overclock in Cinebench. The system sits in a Fractal Design Pop XL Air and the case fans used are three be quiet! Silent Wings Pro 4 in 120 mm in the front, spinning at a quiet 800 RPM, while the rear and top rear each have a 140 mm version at 600 RPM. This is close to an optimal scenario for high airflow at a low noise level.

Temperature results are reported adjusted for room temperature. This means that the result is given as a delta in Kelvin. Simply put, you have to add the room temperature to the result. So, with a delta of 30 K and a room temperature of 22°C, the processor temperature is 52°C. In this way, small temperature fluctuations when performing the test do not affect the result. Or in other words, lower is better.

Let’s get to the actually interesting part. Does the DeepCool Assassin IV just look spectacular or does it perform better than the cheaper AK620? And does a third fan add performance?

One thing up front: I did not perform a volume measurement in this case, but tends to turn out the DeepCool Assassin IV louder than the AK620. In the speed range up to 50%, no real difference is perceptible here, but above that it is quite noticeable. And performance-wise, it’s interesting to see that the AK620 pulls ahead in the high RPM range, at least in this test setup. Albeit largely within the measurement tolerance.

What is evident in the DeepCool Assassin IV review, however, is that it offers a certain performance advantage over its little brother, especially in the low speed range. The slower – and thus quieter – the fans spin, the greater the Assassin IV’s advantage becomes.

And the third fan? Well – DeepCool already knows why the option is given. Because the performance leap is quite noticeable. Of course, this also increases the noise noticeably, so that the cooler is already clearly audible at 50% speed. In return, the performance advantage increases further in the low speed range.

I also further increased the overclocking of the processor up to a power consumption of 180W. And the DeepCool Assassin IV also mastered this without any problems, even if I wouldn’t go below 50% fan power under load here. With this, we are already in the range of the power consumption of processors of later generations and it is good to see that the DeepCool Assassin IV can also sensibly dissipate this heat development, so that you do not have to resort to technically more vulnerable water cooling systems.

The DeepCool Assassin IV proves to be a very strong air cooler in the test, which can set itself apart from the smaller AK620, especially in the low speed range. Add to that the uniquely clean design of the Assassin IV, which clearly stands out from the crowd of air coolers. The premium quality is underlined by the high build quality, which is only marred by the poor fan mounting screws, but this is a negligible problem since almost all fans already come with matching screws as well. Realistically, the much cheaper DeepCool AK620 is still sufficient for most purposes – especially up to upper mid-range processors – and it also offers a certain noise advantage, especially at higher speeds.

Overall, the DeepCool Assassin IV is an outstandingly cool cooler that only has a few weaknesses and impresses with its high performance and special design.

The DeepCool Assassin IV delivers outstanding performance for an air cooler, especially in the lower speed range. Apart from that, it stands out especially in terms of design.