Scythe Fuma rev. B: Surprise with a big question mark

Max. RPM

Improving production by making it cheaper is often done regardless of whether or not a particular product is doing well on the market. Scythe Fuma probably belongs to the “worse category“, which is also proved by its low availability. It seems that the manufacturer had to start to save up to maintain the production. It is no drama, but this tastes a bit bitter because the first version was the best product for its price.

Basic parameters

*These measures indicate distances between the cooler and RAM slots, or more precisely the nearest PCIe × 16 slot.
**The data reflect the situation on Mini-ITX boards which typically have 50 mm from the center of the socket to the first slot. With the ATX format, it can be up to 7 mm more and that means one extra slot and a wider compatibility than is mentioned in the table. We measured the height limit with fans that are aligned with the maximum specified coolers height.

Details

The structure of the heatsink is unchanged, and the basic design is based on two towers. They are relatively narrow, which is good. Reeven Okeanos is also narrow and it can keep up with much wider NH-D15. The area of wider towers is obviously quite inefficient when you consider that heatpipe passages are centered the usual way at the edges. It cannot fully exploit the airflow, and it absorbs less heat.

Fuma is not just narrower but also shorter. Except for NH-D9L (and similar coolers that are optimized for SFF), it is the shortest twin-tower. It is a simple heatsink with two types of ribs. Straight and notched ribs break the air resistance, and slightly dampen aerodynamic noise.

The strength and finish of the heatsink is average. We do not say that there is something wrong about it, but just that Scythe did not consider cosmetics to be the priority, and they invested everything to functional features. Ribs, for example, lack the typical locks to indent them. Frankly, the ribs are quite fragile. The copper parts (the base and heatpipes) are nickel-plated, the rest is aluminum without any other metal, except for the polished top ribs.

Let’s look at the base. This is quite odd. It is convex on one axis (for better contact with the IHS, but the area of the tip is quite small), and concave on the second axis – in the direction of heatpipes (Mugen 5 Rev. B has it in the opposite direction). The pipes are apparently soldered to the base, there are few visible traces of tin.

   

Fans are typical for Scythe – low-end. Only Mugen and Kotetsu have fans with more durable bearings. With Fuma, you can expect just ordinary slip bearings. However, the fan is relatively quiet and no disturbing noise is produced. The sound is constant, and it is not annoying at all (remember SPC Fera 3 v2, that was a bummer).

The operating speed range is better than average with both PWM and fixed voltage regulation which is a bit more complicated. The lower limit is around 350 rpm (3.93 V), but the rotor has to be kicked up a bit with a higher voltage. From a fixed position, it can handle up to 4.85 V (~ 615 rpm).

  

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The assembly kit is decent in every aspect. Some time ago, it used to be the “weakest“ part of all Scythe coolers. But not this time. The mounting system works traditionally – backplate > spacing columns> holders> cross clamp. Compared to the first version, there are AM4 holes on the universal holders, and the clamp is also different. It has fixed screws with springs. The point is that this system is more comfortable to install, especially directly in a case. It is really a good thing that the clasp is one compact unit, and you do not have to put screws into it separately. What is not so good is the fact that you cannot mount the cooler on AMD vertically. It means that airflow is directed to the ceiling and not to the rear panel.

There are three pairs of clamps on the fans, the backplate is metallic, and a small, but decent, thermal compound is part of the accessories. These things are awesome. Another extra part of the accessories is Y multiplug (but you cannot see it in the illustration photo). Scythe did not forget about the owners of very old C2D processors (socket LGA 775), and that is appealing too.

The compatibility with surrounding components is tricky. The fan will overlay the first three memory slots. If you count with a specified heatsink height of 149 mm, you will not be able to use most modules. Even 32 mm is too high. However, you can move the fan – attach it higher if needed. After adjusting it to an average height of about 160 mm, the compatibility issue will be easier to solve.

   

You will not have to deal with a conflicting graphics card. Everything was ok even with our test motherboard which has the first PCIe × 16 relatively close (75 mm away). And if not for the exceeding clamps, the situation could be even better.

Improving production by making it cheaper is often done regardless of whether or not a particular product is doing well on the market. Scythe Fuma probably belongs to the “worse category“, which is also proved by its low availability. It seems that the manufacturer had to start to save up to maintain the production. It is no drama, but this tastes a bit bitter because the first version was the best product for its price.

Test procedures

Tests begin with the analysis of fans. Using the Gophert CPS-3205 II laboratory power supply and the UNI-T UT372 laser tachometer, we detected the initial speed. That means determining the minimum voltage required to move the rotor in the idle stage. Subsequently, we regulated the revolutions by hundreds (from 400 rpm to the round maximum), which gave us the first part of the data to create a curve that indicates the noise increase according to rpm. To make the results as accurate as possible we took the average values of 30 seconds long sequences and regulated the fans by the hundredths of volt until the tachometer reached a specific value, for example 800 rpm. Finally, we noted down the maximum rpm and put values into the parameters table.

   

To assign a specific noise level to a specific speed, we put the coolers with corresponding voltages to the soundproof box in which we measured the noise. This was done using the Reed R8080 sound level meter that was recalibrated before each set of measurements. The positions of the polyethylene pad on which the coolers were fixed, and the sound level meter were always the same. To achieve the most precise logging even with the lowest flow the distance between the sensor of the meter and the fan was approximately 25 cm. Each measurement was performed in real time. The meter sent 30 sound samples to the computer, from which we took the average value and put it into the charts. The most important part was to find and to align the fan settings to fixed noise levels. In this case, 45, 42, 39, 36, 33, and 31 dBA were selected, and with the exception of the last and the penultimate mode, each further decrease of rpm reduced the noise level by a half. On the one side there was noisy 45 dBA and on the other almost completely silent 31 dBA.

If one of the modes is missing in the charts, it is either due to insufficient cooling performance or because it was not possible to regulate the fan to the desired noise level. Each test lasted 600 seconds. We simulated the burn in IntelBurnTest (7500 MB) and the result represents the average of maximum temperatures of CPU cores, which were captured in Core Temp. At the time when some of the cores reached 95 °C, the tests were interrupted and considered unsuccessful.

Cooling performance tests were done in our plexiglass wind tunnel with a motherboard in the vertical position, just like in a usual tower case. The scheme of the system cooling was traditional, balanced flow was provided by four Noctua NF-A12S PWM fans. Two were at the input and two at the output, regulated to 550 rpm.

The intake air temperature was 21 – 21.3 °C, ensured in our air-conditioned lab so we could also accurately measure the automatic regulation PWM. Only during this process we put the processor with TDP 140 W back to the factory settings. The curve of the profile of the impulse modulation was set, regarding to low noise level, to 20 % ≤ 20 °C – 30 % ≤ 40 °C – 40 % ≤ 60 °C – 100 % ≤ 90 °C.

*Without overclocking, the power consumption of the configuration during IntelBurnTest load was around 170 W; 225 W with overclocking (approximately 180 watts by processor).

Improving production by making it cheaper is often done regardless of whether or not a particular product is doing well on the market. Scythe Fuma probably belongs to the “worse category“, which is also proved by its low availability. It seems that the manufacturer had to start to save up to maintain the production. It is no drama, but this tastes a bit bitter because the first version was the best product for its price.

Automatic regulation

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Improving production by making it cheaper is often done regardless of whether or not a particular product is doing well on the market. Scythe Fuma probably belongs to the “worse category“, which is also proved by its low availability. It seems that the manufacturer had to start to save up to maintain the production. It is no drama, but this tastes a bit bitter because the first version was the best product for its price.

Max. RPM

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Improving production by making it cheaper is often done regardless of whether or not a particular product is doing well on the market. Scythe Fuma probably belongs to the “worse category“, which is also proved by its low availability. It seems that the manufacturer had to start to save up to maintain the production. It is no drama, but this tastes a bit bitter because the first version was the best product for its price.

45 and 42 dBA

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Improving production by making it cheaper is often done regardless of whether or not a particular product is doing well on the market. Scythe Fuma probably belongs to the “worse category“, which is also proved by its low availability. It seems that the manufacturer had to start to save up to maintain the production. It is no drama, but this tastes a bit bitter because the first version was the best product for its price.

39 and 36 dBA

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Improving production by making it cheaper is often done regardless of whether or not a particular product is doing well on the market. Scythe Fuma probably belongs to the “worse category“, which is also proved by its low availability. It seems that the manufacturer had to start to save up to maintain the production. It is no drama, but this tastes a bit bitter because the first version was the best product for its price.

33 and 31 dBA

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Improving production by making it cheaper is often done regardless of whether or not a particular product is doing well on the market. Scythe Fuma probably belongs to the “worse category“, which is also proved by its low availability. It seems that the manufacturer had to start to save up to maintain the production. It is no drama, but this tastes a bit bitter because the first version was the best product for its price.

Conclusion

We expected much more form Fuma rev. B. The original cooler was a decent opponent even for NH-D15, the rev. B acts a little bit like some 2nd class cooler. It is only slightly better than the cheaper Fera 3 v2 (and on the top of that, only in low noise modes).

With increasing demands for cooling performance, the pipes are obviously the limiter. Perhaps due to their design, and perhaps due to weaker pressure (we will test the influence of the pressure on the heat transfer intensity soon).

Prints of the compound cannot refute the theory about weak pressure. Compare them with those in this test where we used the first Fuma. Although the convex point is not in the middle of the base, it is positioned identically on both versions. The first one applies more pressure on the processor, which can be proved by tighter contact under convexity and also by more compound on the edges of the IHS. Since the convex point is a bit out of focus, we turned the heatsink 180 degrees, and tested it that way. However, the result did not change (as expected).

With default CPU settings, Fuma is significantly better than Fera 3 v2, but after overclocking (with the CPU around 180 W), the difference is not that significant at all. And it should be the exact opposite, in fact. It is also possible that we acquired a sample that is not 100% representative. We will verify this when we get the appropriate opportunity (assuming we will be able to get another sample – it can be difficult to purchase one because most shops are usually out of stock). And even Scythe itself does not supply samples of this cooler very often, according to available reviews. We’ve found just one review of it on TweakTown, although they tested it with a more cost-effective processor, where the performance deficit does not show up yet. Similar case like Arctic Freezer 33 which starts to “hobble“ only when facing stronger heat intensity.

Sadly, we must say that it does not pay off to get this cooler. Only if you are lucky enough and get a chance to buy the first version – that one is definitely a good deal. If you own Ryzen, you need to order AM4 kit separately.

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• Contents
• Parameters and details
• Test procedures
• Automatic regulation
• Max. RPM
• 45 and 42 dBA
• 39 and 36 dBA
• 33 and 31 dBA
• Conclusion